Hi U.C J. L m Digitized by the Internet Archive in 2012 with funding from University of California, Davis Libraries http://archive.org/details/interimreportcac20cali STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING BULLETIN NO. 20 INTERIM REPORT CACHE CREEK INVESTIGATION COMPARISON OF ALTERNATIVE WILSON VALLEY AND GUINDA PROJECTS ON CACHE CREEK f PRELIMINARY EDITION SUBJECT TO REVISION GOODWIN J. KNIGHT Governor April, 1958 UNIVERSITY OF CAUFOKNi,- DAVIS MAY 19 1958 LIBRARY HARVEY 0. BANKS Director of Water Resources - ■ - STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING BULLETIN NO. 20 INTERIM REPORT CACHE CREEK INVESTIGATION COMPARISON OF ALTERNATIVE WILSON VALLEY AND GUINDA PROJECTS ON CACHE CREEK April, 1958 GOODWIN J. KNIGHT Governor II f* 1 IP mmm ■ HARVEY 0. BANKS er Resources TABLE OP CONTENTS Pag_e LETTER OF TRANSMITTAL . . . . . . . . . , . . . . . . . . . . . vii ACKNOWLEDGMENT „ „ . , , . e . e . „ . „ c „ . „ c . viii ORGANIZATION,, DEPARTMENT OF WATER RESOURCES . . . c . , . . „ „ . Ix ORGANIZATION,, CALIFORNIA WATER COMMISSION . . . „ , . . „ . . „ x CHAPTER I c INTRODUCTION o©ooooooooooooooooool Authorization for Investigation „ „ „ „ . . „ , „ „ c „ » * 1 Objective of the Investigation c " . , . , c o « „ <» o . « » 3 Scope of the Investigation „ «> e <> . . c . « • <> . . » . „ . „ 3 Related Investigations and Reports . „ „ „ „ „ . „ » . „ . „ . 5 Area oi .investigat/ion e»«»«eog»o«o«««»o*0e*oi CHAPTER II. ENGINEERING AND ECONOMIC CONSIDERATIONS . . . . „ . 13 Engineering Considerations „ <> . > . • ■ . o . . « » „ » « <> . 13 Vvd uCI OUppj-N/ oooooooooooooooeooeooooo -L^ water (oiuaj.ii/y •*••••• <> • • ••••»••• » • • o J- o FlOOd HydrOlOgy „ <, o o o o o o o o o e c e o o o o o o o o 20 ourveys a no l^iaps »•••••••••••••••••••»• ^-.l Geologic Exploration C ooooooeoooooooooooo22 Appraisal of Reservoir Lands . » „....<> • • «> e . . » 24 Design and Cost of Structures . „ „ , . c <, . « o . c o . . 25 Economic Considerations • . « « » » . . « » • • . o « « • • o c 26 Irrl^G ulOil ±j6ll6I I vS oooooaoooooooooooooc ^O JL IlO J 0CT/ Ax GSl oooooooocoeoooooooooo ^^/ U J/OjD fa u vGlll ooooooooooooooooooooo O-^- Water Requirements e ■ ■ • <> » » » o <> « « « » « o » « 31 TABLE OP CONTENTS (continued) Page CHAPTER II. ENGINEERING AND ECONOMIC CONSIDERATIONS (continued) Irrigation Benefits (continued) vX UL) X-LuJ-Ub o © © © c © © © » © « o © © o © c © o © • © ,3 £» rdX III iX Xvt-b © O 6 O O © O © O © © © © » C © O © O o © O *■" Crop Production Costs . . . . . . c . . . ...... 32 Net Farm Income , .... » ..... t ..„.„... 33 Computation of Irrigation Benefits . ...» ..... 33 Flood Control Benefits ................... 35 rvecrea uion jDenei its .oeco.o.e. ........ .o jo Hydroelectric Power Benefits . 37 CHAPTER III. WILSON VALLEY AND GUINDA PROJECTS ........ 39 l !P0pi?O J C \j U 0x10. H, LlOnS o © o © © o © © © © « © « • © © © © © © © © ^"U © • © Enlargement of Clear Lake Outlet Wilson Valley Project Geologic Considerations Reservoir Capacity Considerations Wilson Valley Reservoir With Storage Capacity of »OG»0400©r©0© Qooe©o©o« ooo»ec«©o©o o © © o © • o © O © O © «©e©«©oo © • © e o © © 4i 43 45 . 4? . 48 300,000 Acre-Feet (jT0n©2?3J- V 63 Ul-I2?0 S ©o©oooo©o©©©©o©o©o©^'y UUblb o • © o © o o o o o o o o o O © O o © • o o o o o !• -X- 1 X XIIIcj. 1 ^y Xjfei.l"J. X Ob © © © © o e o o 9 a © © © o o © © » o \J J- XjSnGI lU"UOSl/ I\3 UlO ©oeeo©eoo©©©©ee©oo ^Jt- Wilson Valley Reservoir With Storage Capacity of 1, 000 5 000 Acre-Feet ................... 54 Vjr6riG X<3. J- rSa tui/GS oo©»ooeo«cio©e©«©oool/.^ V-/CJSl/Q o o © © © o © © e c © o © o o o © e o © © « o^?^-' ii TABLE OF CONTENTS (continued) CHAPTER III. WILSON VALLEY AND GUINDA PROJECTS (continued) Wilson Valley Reservoir With Storage Capacity of 1,000,000 Acre-Feet (continued) cooooocooooo Primary Benefits . . Benefit-Cost Ratio „ , , . „ . c , , „ © © O « O « o o Guinda Project „ oooooooooooooooceooooooo Guinda Reservoir With Storage Capacity of 303,000 Acre-Feet „ © o © o o o © ©•©ecifroo oooooco© ©•OOO*OOOOO©*O0*O« General Features . c • „ Costs Primary Benefits Benefit-Cost Ratio e e © © o • © © o • o © © © o o 00000*000 OOOO 9*6 Page 58 60 60 62 63 65 67 67 CHAPTER IV. COMPARISON OF WILSON VALLEY AND GUINDA PROJECTS. , 69 Engineering Feasibility General Project Features Project Costs Economic Feasibility Project Accomplishments Project Benefits Benefit-Cost Ratio 00000000000 000 o • • © • O900O000OOO0 oeocooooo«o©o ©•ooe«©o©ooo 0000000009000 oco©©oe«o©co«o CHAPTER V, CONCLUSIONS AND RECOMMENDATIONS vOnc lus ions • •••»•••••••••••• Recommendations « © o 0000000©© o o o • o • • e © • o © o © O 6 • O o • o © © o 69 70 70 70 73 73 75 77 77 80 111 APPENDIXES Page A Reservoir Yield Studies . „ . . <, . » . . .«...* . A-l D UOSTi JlSL-l ITla X»eS a«eoo«oeeoa»«eeeo«o« 1j~-L C Geological Investigation . „ . „ „ , . . . , . , . «, . C-l u oouro jjecrees >«••••••««•«••« <>•••• • d— x E Supplemental Agreement Between State Water Resources Boards County of Yolo,, and Department of Public Works , Dated September 26, 1955 • •••••••••• E-l TABLES Table No 1 Qualitative Classification of Irrigation Waters .... 19 2 Classification of Irrigable Lands in Cache Creek Service Area., Based Upon Source of Water Supply and Major Classes of Use „... •••<>•.•••• 30 3 Estimated Unit Values of Water Requirements for Principal Crops in Cache Creek Service Area . „ . „ . 32 4 Estimated Annual Net Farm Income During the Period of Economic Analysis for Principal urops ?L.n xrojecu Area oooeooooee«oocoo j < 5 Estimated Average Net Farm Income Under Pre- project Conditions in Project Area „ . . . » » . . 42 6 Areas and Capacities of Wilson Valley Reservoir .... 44 7 General Features of Wilson Valley Reservoir With Storage Capacity of 300 ,,000 Acre-Feet . . „ , . . . . 50 8 Summary of Estimated Costs of Wilson Valley Project With Reservoir Storage Capacity of juu^ uuu Acre - 'j^eeT/ •«••»••»•••• •> »•»•• _?-'- 9 Estimated Average Annual Net Farm Income in Project Area With 300,000 Acre-Foot Capacity Reservoir at Wilson Valley . „ . . „ . • . . . . . . 53 10 General Features of Wilson Valley Reservoir With Storage Capacity of 1,000,000 Acre-Feet .... 57 11 Summary of Estimated Costs of Wilson Valley Project With Reservoir Storage Capacity of 1,000,000 Acre- " CC w 600000000 000000000*000 «•! Iv TABLES (continued) Page Estimated Average Annual Net Farm Income in Project Area With 1,000,000 Acre-Foot Capacity Reservoir at Wilson Valley .. . . „ « . . « „ . 59 13 Estimated Average Annual Net Benefits From Wilson Valley Project With Reservoir Storage Capacity of 1,000,000 Acre-Feet . . . . . . . . 60 14 Areas and Capacities of Guinda Reservoir ........ 6l 15 General Features of Guinda Reservoir „ . . . . ..... 66 16 Summary of Estimated Costs of Guinda Project With Reservoir Storage Capacity of 303*000 nOX c~r t." w o o © o © o e 9 o © o o o o © o o o © o © o o OU 17 Estimated Average Annual Net Farm Income in Project Area With 303 <, 000 Acre-Foot Capacity Reservoir at Guinda ............. 68 18 Comparison of General Features of Wilson Valley and (jrUincta .projects oooo.oooo.oo.eooooi-L 19 Comparison of Estimated Costs of Wilson Valley and Guinda Projects ................. .72 20 Comparison of Accomplishments of Wilson Valley and uuincia .rrojecT>s oo.eoooooo..oo..ooiT' 21 Comparison of Estimated Benefits and Costs of Wilson Valley and Guinda Projects . . ......... 76 PLATES (Plates 1 through 6 are bound at end of report) Plate No. 1 Clear Lake-Cache Creek Basin 2 Irrigated and Irrigable Lands 3 Wilson Valley Dam on Cache Creek, Reservoir Storage Capacity of 300,000 Acre-Feet 4 Wilson Valley Dam on Cache Creek, Reservoir Storage Capacity of 1,000,000 Acre-Feet 5 Guinda Dam 6 Comparative Data for Wilson Valley and Guinda Projects v PLATES (continued) (Plates CI through C6 follow Appendix c) Plate No. CI Areal Geology of Upper and Lower Wilson Valley Dam Sites C2 Geologic Sections of Upper and Lower Wilson Valley Dam Sites C3 Possible Sources of Construction Materials, Wilson Valley Dam Site C4 Isoseismal Map for Earthquake of May 7^ 1955 C5 Geology of Reservoir Area and Location of Soil Samples, Guinda Dam Site C6 Surface and Subsurface Geology and Location of Test Holes, Guinda Dam Site VI GOODWIN J. KNIGHT *VEY O. BANKS ADDRESS REPLY TO DIRECTOR p. o. BOX 388 SACRAMENTO 2 11ZON STREET HI CKORY B-471 1 STATE OF CALIFORNIA ifeparimwtt tff Mater Krawrrwi SACRAMENTO April 17, 1958 Yolo County Board of Supervisors County Court House Woodland, California Gentlemen: There is transmitted herewith a preliminary edition of Bulletin No. 20, Interim Report, Cache Creek Investigation, entitled "Comparison of Alternative Wilson Valley and Quinda Projects on Cache Creek", dated April, 1958, This is a report of the investigation conducted by the Department of Water Resources with funds provided by the County of Yolo and the State of California. It is tentatively concluded that either the Wilson Valley or the Guinda Project, with a reservoir storage capacity of about 300,000 acre-feet, would be engineeringly and economically feasible. The estimated benefit-cost ratios for the Wilson Valley and Guinda Projects would be 2.6 to 1 and 2.9 to 1, respectively. In addition, extended studies and analyses indicate that a Wilson Valley Project would return maximum net benefits at a reservoir storage capacity of about 1,000,000 acre-feet, and the benefit-cost ratio would be about 3.2 to 1. It is therefore tentatively recommended that no further consideration be given to the Guinda Project for the conservation of the waters of Cache Creek. In lieu thereof, it is recommended that the Wilson Valley Project which would return maximum net benefits be authorized, and that a feasibility Investigation be initiated. At an early date the California Water Commission and the Department of Water Resources will schedule a public meeting for the purpose of receiving the comments of interested parties. Very truly yours, HARVEY '0. BANKS Director vii ACKNOWLEDGMENT Valuable assistance and data used In this investigation were contributed by agencies of the State and Federal Governments, Yolo and Lake Counties , and by private companies and individuals. This cooperation is gratefully acknowledged. Special mention is made of the helpful cooperation of the State Division of Highways, State Department of Fish and. Game, United States Corps of Engineers, and Yolo County. VI 11 ORGANIZATION DEPARTMENT OF WATER RESOURCES Harvey 0. Banks Director, Department of Water Resources M. J. Shelton .... Deputy Director , Department of Water Resources William L. Berry . . Chief, Division of Resources Planning John M. Haley Chief, Project Development Branch This report was prepared under the supervision of William L. Horn Chief, Local Project Section by M. Guy Pairchild Supervising Hydraulic Engineer Frederick A. Maynard Associate Hydraulic Engineer Principal assistance was furnished by Cole R. McClure, Jr Senior Engineering Geologist James W. Thursby . . Senior Economist Jean Jaquith ....... Associate Hydraulic Engineer John W. Masier . . Associate Hydraulic Engineer Stuart T. Pyle Associate Hydraulic Engineer Richard E. Slyfield .......... Associate Hydraulic Engineer Edward M. Tokunaga ...... Associate Economist B. H. Hoffmaster Associate Hydrographer Engineering designs were reviewed by Walter A. Brown Chief, Supervision of Dams James J. Doody Chief, Dam Design Seccion, Division of Design and Construction Paul L. Barnes .... Chief, Division of Administration Porter Towner ... Chief Counsel Isabel C. Nessler Coordinator of Reports IX ORGANIZATION DEPARTMENT OP WATER RESOURCES CALIFORNIA WATER C OMISSION Clair A. Hill, Chairman, Redding A. Frew, Vice Chairman, King City John P. Bunker, Gustine Everett L. Grubb, Elsinore R. H. Fuidge, Marys ville Phil D. Swing, San Diego Kenneth Q. Volk, Los Angeles George B. Gleason Chief Engineer William M. Car ah Executive Secretary CHAPTER I. INTRODUCTION In March, 1955* the State Water Resources Board, in co- operation with the County of Yolo, made public an interim report of the investigations of the water resources of the Cache Creek Basin . The report presented a plan for a dual purpose flood control and water conservation reservoir at the Guinda site on Cache Creek. Fol- lowing publication of the report, the Legislature requested that an investigation be made of the possibility of constructing a dam at a suitable site in the vicinity of Wilson Valley as an alternative to the development proposed at the Guinda site. In accordance with this directive, the Department of Water Resources of the State of Cali- fornia and the County of Yolo have cooperated in an investigation of possibilities for construction of a dam and a reservoir at the Wilson Valley site, and have compared the engineering and economic feasibility of the Wilson Valley and Guinda Projects This report presents the results of that study,, Authorization for Investigation The Cache Creek Investigation was commenced following an agreement entered into on May 7$ 1954, between the State Water Re- sources Board, the County of Yolo, and the Department of Public Works, State of Calif ornia. The agreement provided for (l) a review of reports of prior investigations of the water resources of the Cache Creek watershed; (2) investigations and studies to determine the present water utilization and the potential service areas for Cache Creek water in Yolo County, the water resources thereof, ultimate irrigable land, water requirements, and preliminary plans and esti- mates of cost for control, development, and utilization of these resources; and (3) the preparation of a report thereon. -1- The State Engineer, upon authorization by the Board, initi- ated the investigation with funds in the amount of $24,000, one-half contributed by the County of Yolo and one-half by the State of Cali- fornia. An interim report on the investigation was published in March, 1955, was approved by the State Water Resources Board, and transmitted to the State Legislature for its consideration. As a result of this report, Assembly Bill No. 3598 was introduced which, when passed by the Legislature and signed by the Governor as Chapter 1950, Statutes of 1955, added Section 12663 to the Water Code. The effect of the action taken by the Legislature was to adopt and authorize the general plan of improvement for flood control and water conservation on Cache Creek, including Clear Lake, in accordance with plans and recommendations set forth in the interim report. However, the following provision was incorporated in the text of Section 12663* "that no funds shall be expended on planning or constructing a dam at the Guinda site below Rumsey on Cache Creek until the Wilson Valley area has been completely investigated and studied and determined by the board not to have comparable engineering and economic feasibility as compared to the Guinda site as recommended in said report." Following passage of the legislation, representatives of the State Water Resources Board, the Division of Water Resources, and the County of Yolo met on July 15, 1955, to plan continuation of the Cache Creek Investigation. A supplemental agreement providing for further investigation, dated September 26, 1955, was formulated as a result of this meeting. The supplemental agreement authorized the immediate ini- tiation of further investigation activities and provided funds to meet the costs of investigation and study of the Wilson Valley area. The estimated cost of the supplemental investigation was $45,000. _2- Of this amount, the County of Yolo made its share, or $22,500 availa- ble to the Division of Water Resources immediately, pending the passage of the Budget Act of 1956, which provided the State's share, also $22,500, and which became available on July 1, 1956. This forward-looking action on the part of the County of Yolo advanced the investigation program by nine months over that which would other- wise have been possible. Since July, 1957, funds provided by the Budget Act of 1957, Item 263 (a) for statewide studies and investi- gation have been utilized to supplement the available cooperative funds . Objective of the Investigation The basic objective of the present study was to conduct engineering, geologic, and economic studies directed to determining the accomplishments of a project at Wilson Valley with a storage capacity equal to that of the authorized Guinda Project, and to com- pare the engineering and economic feasibility of the alternative projects as required by Section 12663 of the State Water Code. In addition, studies were made to determine the size of reservoir at the Wilson Valley site which would yield the maximum net benefits when operated under present conditions of upstream development. Scope of the Investigation The investigation was restricted to the studies necessary to accomplish the stated objectives. Additional planning activity, with consideration given to the reservation of water for upstream use, and to the possibilities of conjunctive operation of ground water and surface storage are both desirable before a definite project proposal is formulated. -3- Factual data developed and presented in the interim report of March, 1955, were utilized in evaluating the Guinda Project. How- ever, previous estimates of project costs and of benefits that would accrue therefrom were re-evaluated so as to reflect present day prices Additional hydrologic studies were made for the purpose of revising estimates of firm yield that could be realized from the Guinda Project, and for determining the firm yield of a reservoir at the Wilson Valley site. Geologic exploration of dam site foundation conditions was conducted at two sites in the Wilson Valley area. In addition, con- struction material borrow areas were located and samples were taken for laboratory testing. Engineering designs and estimates of cost were prepared for several sizes of reservoir storage capacity at the Wilson Valley site. Consideration was given to an upper and a lower dam site, with final selection made of an earthfill dam at the lower site. Economic studies were made to determine the benefits that would accrue from the regulation of the waters of Cache Creek. These included agricultural economic studies to determine the amount of irrigation benefits, and a preliminary re-evaluation of flood control benefits by the United States Corps of Engineers. Finally, detailed economic and operation studies evaluated the comparative accomplishments of the proposed Guinda and Wilson Valley Reservoirs with storage capacities of about 300,000 acre-feet. In addition, the reservoir storage capacity at the Wilson Valley site that would provide the maximum net benefits was determined. ■4- Related Investigations and Reports Numerous prior investigations and reports were reviewed in connection with this investigation. Of major importance are several recent investigations and reports of the Department of Water Resources and of its predecessor, the Division of Water Resources. Following is a brief summary of these investigations . The California Legislature, in recognition of the growing statewide water problem, directed the State Water Resources Board, by Chapter 15^1, Statutes of 19^7* to conduct an investigation of the water resources of California. This study was designated the "State- wide Water Resources Investigation". Funds were provided in the 19^7-^-8 budget for commencement of the investigation and additional funds were provided, through 1955, by subsequent legislative appro- priations. The State-wide Water Resources Investigation was conducted under direction of the State Water Resources Board by the Division of Water Resources of the Department of Public Works. Three bulletins were published containing the results of this investigation. Bul- letin No. 1, "Water Resources of California", published in 1951., contains a compilation of data on precipitation, unimpaired stream runoff, flood flows and frequencies, and quality of water through- out the State. Bulletin No. 2, "Water Utilization and Requirements of California", published in June, 1955* includes determinations of the present use of water throughout the State for all consumptive purposes and presents forecasts of probable ultimate water require- ments, based in general in the capabilities of the land to support further development. The third, and concluding, phase of the State- wide Water Resources Investigation was reported in Bulletin No. 3. entitled "The California Water Plan", published in May, 1957- This bulletin presents preliminary plans for the full practicable develop- ment of the water resources of the State to meet the ultimate water- needs therein, insofar as possible. Information pertaining to the Cache Creek Basin that was assembled for these reports was reviewed and utilized for the pur- poses of this investigation,, As previously stated, an interim report on development of the water resources of Cache Creek, entitled "Cache Creek Investi- gation" was published in March, 1955 . The investigation reported upon comprised studies of the flood control problems of the rim lands around Clear Lake in Lake County and of means for alleviation of these problems, and studies of problems connected with flood control and water supply in Yolo County and of means for conserving the pres- ently wasted waters of Cache Creek. Detailed engineering and geologic studies were made for a dam and reservoir on Cache Creek above the town of Guinda in the upper end of Capay Valley. Much of the basic data presented in the interim report was used in the comparison of the Wilson Valley and Guinda Projects. The Northeastern Counties Investigation, a detailed study of land and water uses and needs covering the major portion of the Sacramento Valley and adjacent areas, also developed data which were used in the Cache Creek Investigation. A preliminary edition of the report of this investigation, entitled "Northeastern Counties Investigation", Bulletin No. 58 of the Department of Water Resources, was completed in April, 1958, and is presently in process of publi- cation. The Legislature, by Chapter 1748, Statutes of 1951, di- rected the Department of Public Works, acting through the State Engineer, to: r -6- "... make an investigation of, and report upon the surface and underground water supplies of the Putah Creek Cone and areas adjacent thereto, in the Counties of Solano and Yolo, .including but not limited to the present utilization of water, future water require- ments, possible sources of supplemental water supplies which may be necessary to meet the present and ultimate requirements therefor, and the Department may incor- porate findings in such report as to the feasible methods of solving the problems involved." The report, entitled "Putah Creek Cone Investigation", incorporating the results of this study, was published in December, 1955. The area investigated included that which lies between Cache and Putah Creeks. Since this area would probably constitute a portion of the service area provided for by a project constructed on Cache Creek, the studies conducted for that investigation are pertinent to, and were used in, the studies and analyses accomplished in the Cache Creek Investigation, An extensive bibliography of additional reports containing data pertinent to the development of the water resources of Cache Creek is to be found in the interim report of March, 1955. Area of Investigation Wilson Valley and Capay Valley, within which lie the alter- native reservoir sites discussed in this report, are located in the southeast and northwest extremities of Lake and Yolo Counties, re- spectively. The principal source of water supply available for regulation at these reservoir sites originates in the watershed of the North Fork of Cache Creek. In addition, substantial quantities of the overflow that periodically spills from Clear Lake could be regulated by either reservoir. Guinda Reservoir also would regulate the flow of Bear Creek, which enters Cache Creek downstream from the Wilson Valley site. -7- Clear Lake is a shallow natural lake situated approximately 110 miles north of San Francisco and 110 miles northwest of Sacra- mento at an elevation of about 1,300 feet. The drainage area tribu- tary to the lake contains about 460 square miles, is generally mountainous in character., and includes several large valleys suitable for diversified agricultural practices „ Along the shore line of Clear Lake are found extensive recreational facilities provided to service the boating, swimming, and fishing activities made possible by the existence of the lake. The communities of Lakeport, Upper Lake, and Kelseyville are the major urban developments. Downstream from the outlet of Clear Lake, Cache Creek descends through a rugged canyon to its confluence with the North Pork, near the upper end of Wilson Valley. From this point, Cache Creek flows some 2.5 miles through Wilson Valley and thence about 18 miles through a canyon into Capay Valley. The entire area down- stream from Clear Lake and above Capay Valley, including the North Fork basin, is a sparsely settled mountainous area interspersed with a few valleys wherein limited livestock grazing is provided by in- digenous areas of open range . The appropriate service area for either the Wilson Valley or Guinda Project lies downstream from the reservoir sites and is divided into an upper and a lower area. The upper area consists of Capay Valley, while the lower area is that portion of the western Sacramento Valley on the Cache Creek alluvial fan in Yolo County. Capay Valley commences at the mouth of Cache Creek Canyon and extends for approximately 16 miles in a southeasterly direction to the western edge of the Sacramento Valley. The floor of Capay Valley varies from about 1 to 3 miles in width. Agriculture, -8- including the production of alfalfa,, deciduous fruits, nuts, and grain, provides the major source of income. Water applied to irri- gated crops is obtained from diversions from Cache Creek, supple- mented by pumping from ground water sources. The dry farming that is practiced depends upon rainfall, which approximates 26 inches in depth annually. Flood damages occur below Rumsey, at the upper end of the valley, during periods of high water when the runoff exceeds the channel capacity of Cache Creeko Limited development has centered in the communities of Rumsey, Guinda, and Capay, The principal area which would derive benefits from the development of Cache Creek lies on the Sacramento Valley floor. The economic development of this area is based almost entirely on agri- culture. Formerly, the major portion of its tillable land was de- voted to the production of grains grown under dry farming methods. The development of irrigation has been accompanied by a greater diver- sification of crops and an increase in production. Principal irri- gated crops include alfalfa, rice, peaches, apricots, almonds, sugar beets, and tomatoes,, Irrigated permanent pasture provides feed for beef, dairy cattle, and sheep . Distribution works for delivering the waters of Cache Creek to parts of the valley service area have been developed by local enterprise. A canal system, including the Capay and Adams Canals, originates at the Capay diversion dam and conveys water along the west, south, and north edges of the lower Cache Creek Basin. Moore Dam, located on Cache Creek approximately 10 miles downstream from Capay Dam, diverts water into the Moore Canal System for distribution to lands lying west of Woodland . These systems are owned and operated by the Clear Lake Water Company . The available water supply is made up of controlled releases and spill from Clear Lake, together with unregulated flow tributary to Cache Creek occurring downstream from the outlet of the lake. Local industry in the Cache Creek Service Area is supported largely by agricultural production. Various plants process meat, dehydrate vegetables and fruit, and refine sugar beets. In addition, packing houses and cold storage plants serve the food processing industry. The expansion of highways and railroad facilities has kept pace with the agricultural and industrial development of the area. The cities of Woodland, Davis, and Winters are the major centers of urban development . The climate of the Cache Creek Basin is characterized by a mild two-seasonal pattern. Approximately 90 per cent of the aver- age seasonal rainfall occurs in the months from November through April. Mean seasonal rainfall varies from less than 16 inches in the vicinity of Davis, to over 50 inches in the highlands on the western edge of the Cache Creek Basin. Winter temperatures seldom fall below freezing, and temperatures of the warm, dry summers frequently exceed 100° Fahrenhe: The average frost-free period in the valley area is about 250 days. Runoff from the Cache Creek Basin is derived principally from precipitation falling as rain. Snowfall occurs rarely and is of little significance as a source of runoff. The majority of the run- off occurs immediately following the rainfall but is prolonged some- what by accretions to the streams from retained soil moisture. However, stream flow diminishes to negligible amounts during the summer and fall. There are springs that maintain a limited flow through the summer, although many contain water of poor quality. The resulting seasonal runoff pattern is one of concentrated winter and early spring floods, and meager summer flows, some of which are of poor quality. -10- In addition to the intraseasonal fluctuations, runoff varies from season to season depending upon the amount of seasonal precipitation. Therefore, in order to develop a firm water supply for the Cache Creek Service Area, it is necessary to provide sufficient storage capacity to facilitate the carry-over of water supplies from years of high precipitation for use in years of low precipitation. -11- - CHAPTER II. ENGINEERING AND ECONOMIC CONSIDERATIONS This chapter discusses the criteria, methods of analysis, and basic procedures used in planning and comparing the proposed Wilson Valley and authorized Guinda Projects The various aspects are considered and discussed under the general headings "Engineering Considerations" and "Economic Considerations" , The features and es- timated accomplishments of the alternative reservoir sites are de- scribed in Chapter III, and an engineering and economic comparison is presented in Chapter IV, A water conservation project may be considered to have engineering feasibility if (l) the water supply is adequate in quan- tity and quality; (2) sites for the dam, reservoir, and other facili- ties are geologically suitable; (3) it can be built with the available materials and techniques and at a reasonable cost; (4) the proposed structures are properly designed and functionally sufficient e In the ensuing discussion the procedures that were used to determine the engineering feasibility of the proposed Wilson Valley and Guinda Projects are described. Terms used in this discussion are defined as follows: Annual The 12-month period from January 1 of a given year through December 31 of the same year, sometimes termed the calendar year. Seasonal Any 12-month period other than the calen- car year. Mean Period A period chosen to represent conditions of water supply and climate existing during a long period of years. As it relates to run- off it is the 53-year period from 1894-95 to 1946-47. -13- Average Period A period chosen during which the conditions of water supply and climate represent the mean period and during which reliable rec- ords are available. For purposes of this report the average period was chosen to be the 45-year average period 1911-12 to 1955-56* Average runoff during this period is about 80 per cent of the mean runoff « Mean The arithmetical average of quantities oc- curring during the mean period c Average The arithmetical average of quantities oc- curring during other than mean periods. Firm Yield The maximum sustained rate of draft from a reservoir that could be maintained through a critically deficient water supply period to meet a given demand for water. For pur- poses of this reports firm yield was assumed acceptable with an average deficiency of 2 per cent per year and a maximum deficiency of 50 per cent during one year of the base period. Water Supply The major portion of the water supply available for regu- lation in a reservoir on the main stem of Cache Creek originates as rainfall in the Upper Clear Lake-Cache Creek Basin. Runoff from snowfall is of limited importance in the basin. Since runoff is largely from rainfall., it is closely allied with the duration and intensity of storms during the winter period. The seasonal runoff pattern is varied^ with large flows occurring in the winter and ear- ly spring,, meager flows occurring in the summer and fall, and both supplemented by limited flow from perennial springs. In addition to variations within the season,, runoff fluctuates widely from sea- son to season. For example-, seasonal runoff in 1930-3-1 was about 10 per cent of the average for the period of record., while in 1940-41 it was about 290 per cent of the average. •14- Under the present method of operation* runoff from the Clear Lake Basin is partially regulated by Clear Lake Impounding Dam* lo- cated on Cache Creek about 5 miles below the natural outlet of Clear Lake Q The Grigsby Riffle, a natural restriction in the channel about 2 miles below the natural lake outlet* limits* under certain conditions* the regulating effect of the dam c The water surface of the lake is controlled* within these physical limitations* as required by the Gopcevic and Bemmerly Decrees Copies of these decrees will be found in Appendix D of this report Natural flows and releases from Clear Lake for irrigation use flow unimpaired down Cache Creek to the first point of diversion in upper Capay Valley In addition to flows from the Clear Lake Basin* the water supply is augmented by the flow of several tributary streams* principally the North Pork of Cache Creek and Bear Creek The seasonal water supplies available for regulation in Wilson Valley and Guinda Reservoirs were determined for the 45-year average period* 1911-12 to 1955~56o The seasonal quantity of water available for regulation by Wilson Valley Reservoir comprises water released and wasted from Clear Lake* runoff of the North Fork of Cache Creek* and runoff from the remaining tributary area below Clear Lake. This quantity was based on measured and estimated natural flows* and a theoretical operation of Clear Lake Monthly stream flow for the North Fork of Cache Creek near Lower Lake* for the period prior to 1931* was estimated by direct correlation with stream flow records of Putah Creek near Winters , The historical record flow was used for the years following 1931. The estimated seasonal runoff to the Wilson Valley Reser- voir from the drainage areas below the Cache Creek gaging station ■15- near Lower Lake, and from the drainage area below the North Fork gaging station near Lower Lake,, was computed from a multiple correla- tion between average annual precipitation and annual flows at seven stations in and adjacent to the Cache Creek Basin These seasonal es- timates were reduced to monthly runoff estimates by proportion with the recorded and estimated monthly runoff of the North Fork of Cache Creek at the gaging station near Lower Lake e In order to determine the releases available for downstream irrigation use without further regulation and the quantity of water wasted from Clear Lake during the mean period, with present (1953) conditions of impairment, a theoretical operation study was made of Clear Lake. The first step in this study was to estimate the pres- ently impaired inflow into the lake c This was accomplished by uti- lizing historical data relating to evaporation, change in storage, re- leases, spills, and combining these data with the present (1953) use of water Secondly, operation studies of Clear Lake were made, using the water supply data determined as above, and imposing the stipula- tions of the Gopcevic Decree. Releases for irrigation use in Yolo County were based on a monthly demand schedule derived from an aver- age of the recorded diversions for the last 15 years. The maximum monthly diversions did not exceed 38,000 acre-feet, and maximum sea- sonal diversion did not exceed 160,000 acre-feet A summary of the operation studies for Clear Lake and various sizes of reservoirs at Wilson Valley are presented in Appendix A, "Reservoir Yield Studies". As the result of the operation studies, the average sea- sonal quantity of water available for storage at the Wilson Valley Reservoir for the average period, 1911-12 to 1955-56, was estimated to be about 276,000 acre-feet, including about 116,000 acre-feet of -16- water spilled from Clear Lake. In addition., an average seasonal irri- gation release of 95*500 acre-feet would be made from Clear Lake and would pass through Wilson Valley Reservoir,, The estimates of seasonal inflow to Wilson Valley Reservoir., segregated into (l) runoff of the tributary area of Cache Creek below Clear Lake Dam including the North Fork of Cache Creek, (2) spill from Clear Lake,, and (3) irrigation release from Clear Lake, are presented in Appendix A. For comparative purposes, operational studies were made of Guinda Reservoir using water supply data similar to those established to evaluate the reservoir at Wilson Valley. The water supply available for regulation in Guinda Reservoir consists of that computed as avail- able to Wilson Valley Reservoir, plus the flow of Bear Creek at the Bear Creek gaging station near Rumsey, and the runoff from the inter- mediate area between Wilson Valley Dam, the Bear Creek gaging station, and Guinda dam site. The runoff record of the station on Bear Creek was extended by correlation with the station on the North Fork of Cache Creek near Lower Lake to obtain a runoff record for the base period. The runoff from the intermediate area was estimated by a multiple correlation similar to that used for the area immediately above Wilson Valley dam site. These studies indicated the average seasonal quantity of water available for storage at Guinda Reservoir for the average per- iod, 1911-12 to 1955-56, would be approximately 359*000 acre-feet, including about 116,000 acre-feet of water spilled from Clear Lake. In addition, an estimated average seasonal irrigation release of 95*500 acre-feet would be made from Clear Lake to pass through Guinda Reservoir. -17- It was assumed that sedimentation in either of the reser- voirs would cause no appreciable loss in storage during the period used for economic analysis of the project. Geologic and ground cover conditions in the basin above the reservoir retard the erosion of large quantities of silt into the stream,, Water Q uality. The mineral quality of surface waters of the Clear Lake-Cache Creek Basin was studied during the initial phase of the Cache Creek Investigation,, Data were obtained from samples collected periodically from Cache Creek at Capay Dam during the per- iod from 1933 to 1939o The conclusions presented herein utilize these data as well as data from more recent samples „ Suitability of water for irrigation use is determined in accordance with the following criteria ; The minerals recognized as the principal criteria for qual- ity classifications ares (l) total dissolved mineral solids; (2) chloride concentration; (3) percentage of sodium; and (4) boron concentration,, Irrigation waters are divided into three broad groups ass Class I Excellent to good, or suitable under most conditions Class II Good to injurious,, or harmful to some plants under certain condi- tions Class IIX Injurious to unsatisfactory, or harmful to most plants under most conditions These limits are presented in Table 1. ■18- TABLE 1 QUALITATIVE CLASSIFICATION OF IRRIGATION WATERS Chemical properties Class I Excellent to good Class II Good to injurious Class III : Injurious to ; unsatisfactory Total dissolved solids In ppm In conductance EC x 10 u at 25^ C Chloride, in ppm Sodium, in per cent of base constituents Boron, in ppm Less than 700 TOO - 2,000 More than 2,000 Less than 1,000 1,000 - 3.000 More than 3,000 Less than 175 175 - 350 More than 350 Less than 60 60 - 70 More than 70 Less than 0.5 0.5 - 2,0 More than 2.0 Class II irrigation water is of doubtful suitability, under certain conditions, for low-salt-tolerant crop plants, including cit- rus and deciduous fruit, several vegetables, and most clover grasses. Class III water is ordinarily unsatisfactory for all crops except the more tolerant plants such as cotton, beets, and salt-tolerant forage grasses o These criteria have been found to be limitations in actual practices „ In many instances a water may be wholly unsuitable for ir- rigation under certain conditions of use and yet be completely satis- factory under other circumstances 6 Soil permeability, temperature, humidity, rainfall, and other contributing conditions must be con- sidered in addition to quality classification of a water for irriga- tion use. Water released through Clear Lake Dam is moderately hard, due to its predominant mineral content of calcium bicarbonate „ Its high concentration of boron, ranging from C 7^ to 1.4 parts per mil- lion, lowers the quality classification from Class I to Class II„ -19- Below the confluence of the main stream and the North Fork of the stream, the water is classed as "very hard" because of the high content of the bicarbonates of sodium and calcium. In addition,, it contains concentrations of boron varying from o 3 to 7«2 parts per million,, However., in either of the reservoirs under consideration, the mixing of the slightly better water of Cache Creek with that of the North Fork would probably result in a more uniform, moderately hard water Also, in either reservoir, the boron content, the major degradant to Cache Creek water, would be reduced in concentration as the result of storing and mixing the better quality waters occurring during high flows with the poorer waters of low flows. Bear Creeks with its many mineralized springs, is a major contributor of degradants c Mineralized waters originating on the west slope of Capay Valley add to the degradation of the water sup- ply o However, with the construction of the Guinda or Wilson Valley Project, the water containing these degradants would be improved by mixing with the better water of Cache Creek It has been concluded, therefore, that the boron concen- tration of the regulated water at Capay Dam under operation of either Wilson Valley or Guinda Reservoir would probably average between l o and 1„5 parts per million. The water in either instance would be a calcium carbonate type and would be classified as "good" for general beneficial uses. Flood Hydrology The estimate of the peak flood inflow into Wilson Valley Reservoir was developed from a regional study of flood frequencies and unit hydrographs. The once-in-1, 000-year flood was selected for -20- use as the spillway design flood,, This flood hydrograph was developed by routing a theoretical once-in-1, 000-year flood through Clear Lake and superimposing thereon a second hydrograph based upon known hydro- logic conditions in the region comprising the remainder of the drain- age area above Wilson Valley dam site The characteristics of an estimated once-in-1, 000-year flood in Kelsey Creek near Kelseyville were used as the basis for the flood flow estimates for the Clear Lake Basin c The flood developed by this procedure was then routed to Wilson Valley Reservoir through an assumed enlarged outlet channel from Clear Lake into Cache Creek„ The enlarged channel would have a capacity of 8,500 second-feet when the water level at the Rumsey gage was 7»56 feet It is estimated the flood resulting from these operations, when combined with the maximum runoff of the tributary drainage area of Cache Creek above Wilson Valley reservoir site, would yield a peak inflow to the reservoir of 84,000 second-feet „ Prior to 1958, the maximum flood recorded at the United States Geological Survey stream gaging station "Cache Creek near Capay" occurred January 21, 1943.? and amounted to 27,500 second-feet The estimated flood peak at this station on February 24, 1958, sub- ject to later verification, was 52,000 second-feet Surveys and Maps Topographic maps of the reservoir area and dam sites in Wilson Valley were obtained from the United States Bureau of Recla- mation„ The maps were prepared at a scale of 1 inch equals 400 feet, with a contour interval of 20 feet Topographic maps of the Guinda reservoir area at a scale of 1 inch equals 400 feet with a contour •21- interval of 20 feet were obtained by the Division of Water Resources in 195^ o Other maps used in the investigation were United States Geological Survey quadrangles., at a scale of lc62,500 with a contour interval of 50 feet. Geologic Exploration Preliminary geologic explorations were conducted to investi- gate the foundation conditions at the Wilson Valley and Guinda dam sites. The Wilson Valley site was explored during 1955 and 1956, un- der the present phase of the Cache Creek Investigation., and Guinda dam site was explored in 1953 • The objective of the geologic explorations was the selection,, from a design and construction standpoint, of the most desirable site, and the procurement of data to assist in the design of the dam and appurtenant structures. The exploration programs consisted of sur- face inspection and geologic mapping of the dam and reservoir sites; test drilling along the axes of the proposed dams and in the abut- ments and spillway areas; the collection of soil samples to deter- mine the construction properties of available materials; and the determination of quantities of available construction materials. In studying the dam sites , particular attention was given to determina- tion of the rock types, degree of weathering, patterns of jointings and the nature and extent of shear zones. These factors influence the required designs and indicate probability of leakage through the foundation of the dam. Depths of stripping necessary to expose suitable foundation for earthfill dams were determined from the drilling programs. Detailed reports of these investigations are included in Appendix C. -22- Two possible dam sites were explored at Wilson Valley 5 an upper and lower site The upper site is at a constriction in the can- yon of Cache Creek immediately below Wilson Valley,, The lower site is about 1 mile farther downstream c Locations of these sites are shown on Plate CI of Appendix C The geologic exploration in Wilson Valley resulted in the conclusion that the lower site was better suited to the construction of an earthfill dam to the required height Factors leading to this conclusion were the more favorable topographic conditions,, a lesser amount of fracturing and faulting of the foundation and abutment rocks., and better foundation conditions resulting in a lessened possibility of leakage o Other considerations were the reduced quantity of strip- ping necessary to expose suitable foundation conditions in the chan- nel and abutment sections,, and a lesser requirement for blanketing and lining the spillway due to the greater impermeability and stabil- ity of the underlying material „ The geologic exploration at the Guinda dam site* located just north of the town of Guinda., included surface inspection and test drilling. This site is in an alluvium-filled valley , in con- trast to the rocky canyon at the Wilson Valley site. A seismic sur- vey along the axis of the dam and a detailed exploration of Capay Valley in the vicinity of the reservoir site were made The site was found to be suitable , although extensive excavation may be nec- essary in order to provide a suitable cutoff to prevent leakage „ At the site selected, an adequate spillway location could be lo- cated through an existing saddle behind the left abutment e -23- Appraisal of Reservoir Lands Preliminary estimates were made of the value of lands, im- provements., and public utilities within the alternative reservoirs under consideration,, An appraisal made of the Guinda reservoir site in January., 1955 » was re -evaluated on the basis of current economic conditions during the present phase of the investigation s In addi- tion., a new survey was made of Wilson Valley dam and reservoir site in February , 1957 <> Real estate was evaluated by the market analysis method in which each tract of land is appraised by comparison with recent trans- actions in which similar properties were involved „ Data on land ownership , and descriptions of properties , were obtained from the County Assessor,, and data on recent sales and costs of properties, in and adjacent to the areas,, were obtained from the County Recorder and from local real estate agencies „ Estimates of the value of improve- ments and public utilities were made separately., based upon replace- ment costs o Improvements include buildings., structures, private water systems P and private irrigation works „ Public utilities in- clude highways, roads, telephone and electric power lines, municipal water works, and irrigation service agency works „ Replacement costs were estimated as the expenditure required under existing conditions to replace a structure with a similar one of comparable utility. For purposes of this report it was assumed that the market value of land and property would represent the present worth of the future productivity of lands flooded by reservoir development. Estimates were also made of damage that might accrue to a property owner because of adverse effects of a public works proj- ect, including severance of property; reduction of area of -24- operation; loss of, or obstructions to, communications; loss of arable lands by reason of flooding; and other elements „ All developed lands, as well as the accessible portions of the undeveloped lands within the reservoir areas, were inspected and evaluated in the field. Cost estimates of proposed highway relocations were made in cooperation with the State Division of Highways. Design and Cost of Structures Engineering designs were made of several sizes and types of earthfill dams at the lower Wilson Valley site, primarily to determine the capital and annual costs of the required structures. Data dis- cussed previously in this chapter were used as the basis for these de- signs and cost estimates . Features selected for construction may be modified with future design studies, but are considered adequate to provide reliable cost estimates. The estimates of cost are considered adequate for the purpose of comparing the engineering and economic feasibility of alternative proposed projects. Designs and estimates of cost for the Guinda Project were made during the initial phase of the Cache Creek Investigation. No revisions of this work have been made other than to modify the costs of the Guinda Project to reflect present-day prices. Structures were designed in accordance with standard engi- neering principles, with the objective of obtaining the most econom- ical combination of dam embankment, spillway, and outlet works. The dams were designed to be constructed of available natural materials, with adequate consideration being given to foundation conditions. Stability characteristics of the embankments were based on laboratory ■25- tests of sampled materials. Spillways were sized to pass the design floods using surcharge storage above the spillway crest to reduce the peak outflow. Estimates of capital cost for each project include construc- tion costs of the dam and appurtenances, acquisition of reservoir and dam sites,, and relocation of public utilities. Capital costs are based on unit prices prevailing as of the fall of 1957* Also included are allowances of 10 per cent of the total cost for engineering and administration and 15 per cent of the total cost for contingencies in construction. Interest during construction was added to the capital cost in the amount of 4 per cent per annum for one half of the con- struction period. Annual costs include interest on the capital investment at 4 per cent per annum, amortization of a 50-year period on a 4 per cent sinking fund basis., and the annual outlay required for replace- ment , operation and maintenance , and general expense. It is believed that the features of the projects as pre- sented herein reasonably represent those which would be selected for construction to meet the stated accomplishments. Changes in design would probably be made after further exploration of the sites and more thorough design analysis. However, the costs estimated for the Wilson Valley Project are adequate for comparison with the previous estimates for the Guinda Project, and for the purpose of evaluation of engineering and economic feasibility. Economic Considerations Economic studies were made to determine the benefits that would accrue from a reservoir at the Wilson Valley site, as well as -26- from a reservoir at the Guinda site. These benefits were used in comparing the economic accomplishments of the two alternative proj- ects. The principal benefits realized from either project would be those resulting from an increase in agricultural income. Studies to determine irrigation benefits included detailed analyses of the pos- sible service area to determine the extent of presently irrigated lands, probable crop pattern under project conditions, estimates of water requirements, and net farm income that would accrue to the service area under various project conditions. Other factors of importance in evaluating and comparing the projects are the benefits that would accrue from flood control pro- tection and from recreation made available as a result of the reser- voir development A preliminary estimate of flood control benefits was obtained from the United States Corps of Engineers Recreation benefits, including a study of the enhancement of the stream for fish and wildlife purposes, that would be realized with project development were investigated but not evaluated in monetary terms. The following terms are used as defined in connection with the ensuing discussion; Consumptive Use of Water . Water consumed by vegetative grown in transpiration and building of plant tissue, and water evap- orated from adjacent soil, from water surfaces, and from foliage. Also water similarly consumed and evaporated by urban and nonvegetative types of land use. Farm Irrigation Efficiency The ratio of consumptive use of applied irrigation water to the total amount of water de- livered to the farm, commonly expressed as a percentage. Farm De livery. The amount of water delivered at the farm head gate to provide for all beneficial uses, and for irre- coverable losses incidental to such uses. Benefits . The identifiable increases or gains in assets or values resulting from a project, either as tangible goods or services or as intangibles, either primary or secondary, which take account of conditions "without" and "with" the project. Only primary benefits are considered in the evalu- ation of projects in this report. -2?~ Primary Benefits . The identifiable net values of the goods or services resulting directly from the project,, obtained by deducting from the gross benefits all costs of realization except the economic costs of the project. Examples of primary benefits are the net savings in transportation costs , the flood or other damages pre- vented, the net value of power produced, etc Economi c Feasibility This term.;, used in the authorizing legislation, was construed to refer to the determination of the relationship between costs incurred in, and the benefits which are derived from, the construction and operation of a water development project. It is expressed as an arithmetic proportion of esti- mated average annual benefits to average annual costs, and termed "benefit-cost ratio" Net Far m Income. The residual amount of gross receipts less cost of production, excluding water cost and management charges . Repayment Period , The period of time, commencing with the year a facility or project becomes operational or at the end of an allowable development period, during which all reimbursable costs as well as annual operation, maintenance, and replacement costs will be paid by project beneficiaries. For this study the period of time is considered to be 50 years. In making the analysis of economic feasibility only tangible primary benefits were used. In the final selection of a project^ con- sideration should also be given to secondary and intangible benefits. The optimum size of the Wilson Valley Project was consid- ered to be that at which the incremental benefit just equaled the incremental cost, as determined by consideration of costs and of flood control and irrigation benefits. A project of this size would yield maximum net benefits from the available water supply. The benefits of the proposed projects accrue primarily from new irrigation supplies, flood control, and recreational oppor- tunities, and these factors will be discussed in the following sec- tions. Irrigat ion Benefits By means of irrigation it is possible to cultivate a wide variety of crops in the Cache Creek Service Area and to obtain -28- a much greater crop yield than is possible with dry- farming operations Present irrigation development in this area reflects maximum use of the partially regulated available surface water supply which is supple- mented by ground water pumping,, Project development would provide a basis for increased agricultural productivity and income in the ser- vice area by making new firm water supplies available to replace the present unregulated and fluctuating seasonal flows In addition to primary irrigation benefits, secondary benefits would result from the associated stimulus to the local economy . Project Area,, The Cache Creek Service Area., provided for by either the Guinda or Wilson Valley Projects,, consists of lands within the lower Clear Lake-Cache Creek Basin in Yolo County. The general area., delineated on Plate 2, is bounded on the north by the Colusa Trough Drainage Canal, on the east by the Yolo Bypass,, on the south by Putah Creek, and on the west by the easterly slopes of the Coast Range o Water could not be provided from the projects under consideration for all irrigable lands within this general area c For the purpose of economic analysis,, it was necessary to limit the ex- tent of the service area to those lands which could be served from the water supply made available from each alternative project Such portions of the service area are titled "Project Area" and are given only in terms of area and not delineated » Data on the extent of irrigable and presently irrigated lands, as compiled for the "interim Report, Cache Creek Investiga- tion", were used in this study Present land use was based on land use surveys made by the Division of Water Resources during 1952, 1953* and 1954. At that time it was estimated that there were about 120,000 acres under irrigation in the service area -29- The irrigable lands shown in the interim report were deter- mined from a land classification survey conducted by the United States Bureau of Reclamation in 19^4, with minor modifications by the Division of Water Resources A total of 264,000 acres was classified as irri- gable . After subtracting lands irrigated by ground water, lands within the Yolo-Zamora Water District,, urban lands,, and fallow lands used in rotation with lands irrigated by ground water, it was esti- mated that a gross area of 158,700 acres could be considered as a possible service area for the waters of Cache Creek 9 This area in- cludes lands presently utilizing water diverted from Cache Creeko A breakdown of the land areas comprising the total irrigable land in the Cache Creek Service Area is shown in Table 2. TABLE 2 CLASSIFICATION OP IRRIGABLE LANDS IN CACHE CREEK SERVICE AREA, BASED UPON SOURCE OF WATER SUPPLY AND MAJOR CLASSES OF USE Classification ' Area, in acres Total irrigable land in Cache Creek Service Area 263,900 Lands from which benefits were not considered Land irrigated from ground water supply 63,200 Irrigable land in Yolo-Zamora Water District 19,000 Fallow land used in rotation with lands irrigated from ground water supplies 11,000 Urban lands 12,000 Subtotal Possible project area for either the Wilson Valley or Guinda Project •30- Crop Pattern,, The crop patterns in the service area that would be irrigated under the projects considered herein were based upon the present crop pattern., upon data presented in the publication of the United States Department of Agriculture, Bureau of Soils, "Soil Survey of the Woodland Area., California", and upon all available re- cent information relating to the adaptability of crops to the soil conditions and climatic characteristics of the area. Such factors as crop rotation requirements, acreage limitations of crops, and water costs were also considered. Water Requirements. The quantity of water required for use by irrigated crops was estimated from unit values of consumptive use of applied water and appropriate farm irrigation efficiency factors. Conveyance losses were added to this value to determine the water re- quirement at the point of diversion. Unit values of consumptive use of applied water were esti- mated from direct measurements of consumptive use for crops grown on the University of California farm at Davis, and from correlations of these data with climatological factors. Much of the data relating to estimates of demand for irrigation water, as well as water require- ments for uses other than irrigated crops, was based on information compiled for the statewide water resources investigation, the results of which were published by the State Water Resources Board in Bulle- tin No. 2, "Water Utilization and Requirements of California". Unit values of consumptive use of applied water, farm irrigation effi- ciency, and farm delivery for crops in the Cache Creek Service Area are presented in Table 3° -31- TABLE 3 ESTIMATED UNIT VALUES OF WATER REQUIREMENTS FOR PRINCIPAL CROPS IN CACHE CREEK SERVICE AREA ; Consumptive Farm : Farm 8 use of : Irrigation : delivery, Crops :applied water, : efficiency, : in ; in feet i In : feet : of depth : per cent : of depth Fruits and nuts Almonds 1.5 75 2.0 Apricots 2 75 2.7 Prunes 2.0 75 2.7 Walnuts, peaches 2.5 75 3.3 Field and truck Alfalfa 2.7 75 3o5 Irrigated pasture 3c0 70 4.3 Sugar beets 1.8 75 2.4 Tomatoes 2.0 75 2.7 Beans, Milo, etc 1.5 75 2.1 Melons and other truck 1.5 70 2.1 Rice 4.1 75 9.0 Crop Yields. Crop yields for both irrigated and dry-farmed crops were assumed to be in the range of "usual" to "good". Data were based upon reports of the Yolo County Agricultural Commissioner and upon the experience of local farmers. Typical yields used for deter- mination of benefits are shown in Table 4. Farm Prices . Average prices received by farmers at the first point of delivery during the 10-year period, 1946 through 1955> as reported in the Yolo County Agricultural Commissioner's Annual Reports, were assumed to prevail during the period of economic analy- sis. Crop Production Costs . Crop production costs were derived from labor and material requirements reported In California Agri- cultural Extension Service crop-enterprise studies, to which were -32- applied average unit costs during the 10-year period of 1946 through 1955o Production costs per acre for generally accepted economic size farm operations under average management abilities were computed., The costs include hired and operator's labor, use of farm machinery and equipment,, materials used in production,, interest on investment, de- preciation, taxes, insurance, and miscellaneous charges; they exclude cost of project water and management charges „ Hourly farm wages of $0 o 85 and $1„00 for unskilled and skilled labor, respectively, were used c Tax costs were computed at the current rate utilized in Yolo County,, Interest costs on farm in- vestment were assumed to be 5 per cent of inventory value „ Net Farm Income «, Net farm income was considered to be the residual of gross receipts from farm production less the cost of pro- duction, excluding water cost and management charges. The net farm income on a per acre basis for the principal crops in the service area is presented in Table 4„ Computation of Irrigation Benefits , Net farm income from the service area was computed for an irrigable area of 158,700 acres for (l) preproject, or existing, conditions assuming an average diver- sion of 105,000 acre-feet seasonally at Capay and Moore Dams, (2) a 300,000 acre-foot storage capacity reservoir at Wilson Valley and an average diversion of 142,000 acre-feet seasonally at Capay and Moore Dams, (3) a 1,000,000 acre-foot storage capacity reservoir at Wilson Valley and an average diversion of 252,000 acre-feet seasonally at Capay and Moore Dams, and (4) a 303,000 acre-foot storage capacity reservoir at Guinda and an average diversion of 158,000 acre-feet seasonally at Capay and Moore Dams* -33- TABLE 4 ESTIMATED ANNUAL NET FARM INCOME DURING THE PERIOD OF ECONOMIC ANALYSIS FOR PRINCIPAL CROPS IN PROJECT AREA Crops : Yield, i\j n ^ :per acres Price ; Per ^"'r-SrSIs in dollars Monetary values per acre, in dollars Irrigated Almonds 1,500 lbs. 0.27 b 405 227 178 Apricots 5.0 ton 127 . 00 635 450 I85 Prunes 1.9 ton 200.00 380 270 110 Walnut 1,600 lbs. 0.24 b 384 210 174 Peaches, Freestone 8.5 ton 56.00 476 300 176 Alfalfa 6,0 ton 24.30 146 100 k6 Pasture 11.0 AUM a 7.oo c 77 46 31 Sugar beets 19°0 ton 13.20 d 251 178 73 Beans , dry 12.0 cwt. 10.50 126 97 29 Corn, field 4o.o CWtc 3.50 l4o 100 4o Rice 30 oO cwt. 4. 60 138 96 42 Milo 23«0 cwt. 3.10 71 51 20 Tomatoes, processing 17.0 ton 25.00 425 319 106 Melons and others 200 crate 2.40 480 400 80 Dry farmed Almonds 600 lbs. 0.25^ 150 139 12 Prunes 1.0 ton 180.00 180 160 20 Walnuts 900 lbs. 0.22 b 198 170 28 Small grains Rotation 20 cwt. 2.70 54 35 19 Other 6 cwt. 2.70 16 10 6 Pasture 2 AUM a 7„oo c 14 10 4 Native vegetation 1 AUM a 7-oo c 7 5 2 a - Animal unit month. b - Price differential allows for better shelling quality with irrigation c - Based on pre -cut alfalfa equivalent price. d - Includes subsidy payments . •34- The Irrigation benefit for each of these projects was then evaluated as the increase in net farm income for the service area over and above the net farm income for the service area under preproject conditions. The results of irrigation benefit computations for each project are presented in Chapter III C Flood Control Benefits Analyses of the proposed Wilson Valley and Guinda Projects were made to determine the benefits that would accrue from the pro- tection afforded by flood control operations. Flood control benefits would accrue to areas downstream from Guinda Reservoir,, and approxi- mately the same annual benefits would be realized from the creation of similar facilities at Wilson Valley. In order to determine a preliminary estimate of the annual value of flood control benefits., an informal discussion was held between the Corps of Engineers and the Department of Water Resources <> This resulted in a tentative agreement on the amount of flood control benefits that would accrue from a storage reservation for flood control only of 65*000 acre-feet on Cache Creek. In the analysis of flood control benefits resulting from the operation of Wilson Valley Reservoir, it was indicated that the reservation of flood control storage and the installation of flood control outlet works would not be economically justified for a res- ervoir with a storage capacity of 300,000 acre-feet, but a flood control storage reservation of 65,000 acre-feet would be justified for a reservoir with a storage capacity of 1,000 ,,000 acre-feet. However, it should be noted that the inherent regulatory effect of -35- the smaller reservoir would reduce peak flood discharge and would re- sult in appreciable incidental flood control benefits. No evaluation of incidental flood control benefits was made for this study. The protection of real estate from loss or damage by flood- waters would result in appreciable benefits to the area. Additionally., there would be a reduction in crop losses from land temporarily re- moved from production and from the interruption of business and trade. Recreation Benefits The construction of either Wilson Valley or Guinda Reser- voirs would enhance recreation opportunities by providing a setting for the development of facilities such as camp sites, boating facili- ties, and summer homes. Also, additional recreation opportunities would result from the enhancement of flows in the Cache Creek channel. It should be noted that because of the proximity of Clear lake, recre- ation development may be somewhat retarded as compared with reservoirs in areas with fewer existing facilities. Because of legislative limitations placed on the studies for this report, the monetary value of recreation benefits that would accrue from the two projects was not evaluated. There are indications, however, that Wilson Valley Reservoir would provide greater benefit to fishing and water-associated recreation than would Guinda Reser- voir. Further, Wilson Valley Reservoir would provide an opportunity for the improvement of an additional 23 miles of stream for fish and wildlife enhancement than would be provided by Guinda Reservoir. In selecting and authorizing a project for construction in the Cache Creek Basin, the recreation benefits for each proposed project should be evaluated and suitable areas adjacent to the reservoir should be reserved for recreation use and development. -36- An alternative method of operating the projects to that presented herein to enhance the recreational aspects of Clear Lake should be evaluated. Consideration should be given to a method of operation whereby Clear Lake fluctuations would be held to a minimum, except during the critical dry period, and all releases would be made from the storage reservoir on the main stem of Cache Creek. Under an alternative plan of operation, involving minimum fluctuation in the water surface of Clear Lake, recreational use of the downstream res- ervoir would be affected adversely. The recreational benefits that would accrue under such a plan should be evaluated prior to decision on the plan of operation for the project. Hydroelectric Power Benefits Because of limitations imposed on this study, no investiga- tion was made of possible hydroelectric power developments as a re- sult of additional storage on Cache Creek. Future study of major water conservation projects in Cache Creek Basin should give consid- eration to multipurpose operation which would include hydroelectric power generation. -37- CHAPTER III. WILSON VALLEY AND GUINDA PROJECTS This chapter sets forth the general features and. estimates of costs of the projects considered for the Wilson Valley and Guinda sites and an estimate of the benefits that would accrue therefrom. Based upon these data, projects will be compared in a subsequent chapter with reference to accomplishments and the relationship between benefits and costs. Investigation of the Wilson Valley reservoir site included a study of the hydrology of the basin and the water requirements of the service area In order to establish the general features of the project. It also included geologic studies and an investigation of available construction materials to provide the basis for design of the physical features of the project. Finally., the costs of the proj- ect and its accomplishments,,, in terms of water yield, flood control , and recreation potential, were determined. In order to encompass the range of possibilities of the Wilson Valley site, four sizes of reservoir were considered. The smallest project considered would have a storage capacity of 300,000 acre-feet, comparable in size to that of the Guinda Project. The largest project considered would have a storage capacity of 1,000,000 acre-feet. Between these limits, studies of other sizes of proposed projects established a scale, or "yard stick", from which the project possessing the maximum benefits in relation to costs could be selected As previously discussed in Chapter II, project benefits from irrigation water were computed as the increase in net farm income that would be realized as a result of the change from pre- project to project conditions. Flood control benefits were deter- mined jointly with the United States Corps of Engineers. Recreation -39- benefits., however, were studied only to the extent required to estab- lish their probable existence but were not evaluated in monetary terms . No additional engineering investigation was performed in connection with the Guinda Project „ However, the features of this project are presented in this chapter for comparative purposes. The costs of the Guinda Project were increased by standard cost index factors in order to approximate current costs of construction. How- ever , no adjustment was made to account for additional costs result- ing from increases in the estimated cost of relocating State Highway No. 16 around the reservoir, nor for increases in the estimated cost of the spillway structure required to pass the current revised esti- mate of flood flow. Estimates of benefits that would accrue to the Guinda Project were reviewed during this investigation and adjusted so as to be comparable with those determined for the Wilson Valley Project • Preproject Conditions A theoretical standard of comparison for the Project Area was used as the basis for the evaluation of gains or loss in net farm income resulting from the development of a water resources proj- ect,, This standard is termed "preproject conditions", and is assumed to be an average condition throughout the period of analysis. It was assumed that the historical average seasonal diversion of 105,000 acre -feet at Capay Dam on Cache Creek near Capay would be the water supply available to the service area. This diversion was reduced by 20 per cent to account for conveyance losses. The quantity of water was then distributed to lands supporting an average crop pattern, -40- based on previously discussed unit values of water requirement and the recent crop pattern. Table 5 illustrates the derivations of the resultant average net farm income used as the base from which project benefits were determined. Enlargement of Clear Lake Outlet As previously stated, water supply studies for this investi- gation were made under the assumption that the Clear Lake outlet channel would be enlarged. The former Division of Water Resources recommended, in its "Report on Clear Lake-Cache Creek Flood Control Investigation", 1939* that the outlet be enlarged to a capacity of 8,500 second-feet when a lake level of elevation 7° 56 feet existed on the Rumsey gage. The existing outlet capacity with the lake at 7-56 feet is about 2,500 second-feet. The maximum flow is now limited by the Grigsby Riffle rather than the Clear Lake Impounding Dam. Improvements to the outlet channel would permit lake level control and thereby alleviate flood damage to suburban and recreation develop- ments on the perimeter of Clear Lake. Enlargement of the channel capacity would require modifica- tion of the Gopcevic Decree and dismissal of the Bemmerly Decree. Clear Lake would continue to be operated within the levels specified in the Gopcevic Decree, but the restriction against deepening the channel over four feet below zero on the Rumsey gage would be removed. Dismissal of the Bemmerly Decree should be possible when a water conservation and flood control project providing flood protec- tion for lands along Cache Creek in Yolo County is constructed. It has been previously estimated that the enlargement of the Clear Lake outlet could be made at a capital cost of approximately -41- TABLE 5 ESTIMATED AVERAGE NET FARM INCOME UNDER EREPROJECT CONDITIONS IN PROJECT AREA Area Land utilization and crop pattern Per : Acres cent: Seasonal farm delivery :Acre-feet : per : Total, in : Annual ; net farm income :Per acre, : Total, : in : in acre :acre-feet: dollars : dollars Irrigated Lan d Field crops Alfalfa Pasture Rice Sugar beets Tomatoes Others Subtotals Orchards Almonds Apricots Others Subtotals Fallow (dry-farmed grain) Subtotals Subtotals, Irrigated Land Dry-farmed Land Field crops Small grains Pasture Others Subtotals Orchards Almonds Others Subtotals Fallow Subtotals Subtotals, Dry-farmed Land Native Vegetation Subtotals, Native Vegetation TOTALS, PROJECT AREA 2 • 5 4,000 3-5 14 ,000 46 184 000 1 • 9 3,000 M 12 ,900 31 93. 000 2 • 3 3,700 9-0 33 ,300 42 155. 000 1 • 5 2,500 2.4 6 ,000 72 180 000 1 .3 2,000 2.7 5 ,400 106 212; 000 .0 4,800 20,000 2.1 10 81 ,100 ,700 53 255. 000 12 • 5 1,079, 000 .8 1,200 2.0 2 ,400 178 214 000 .1 200 2.7 500 185 37, 000 .1 100 1,500 3.0 3 300 ,200 173 ■ Hi 268, 000 1 .0 000 2 • 5 4,000 "^+,000 _JL_ _ 19 76, 000 2 • 5 - ,000 16 .0 25,500 - 84 ,900 - 1,423, 000 44 .4 70,600 6 424 000 16 .5 26,200 - - 4 105. 000 .9 15 1,200 98,000 _Z_ _ __4 . p 534, 000 61 - 000 2 .2 3,500 . „ 12 42, 000 .1 200 3,700 _I_ - 13 — T^ 000 2 • 3 - 000 11 .0 .0 17,500 17,500 — — _ — — - 11 - - 75 .1 119,200 - - - 579; 000 8 •9. • 9 14,000 14,000 -Z— _ _2 28, 28, 000 8 - 000 100 .0 158,700 m 85. 000* _ 2,030, 000 Estimated quantity of water delivered at farm head gates, based on average annual diversion of 105,000 acre-feet at Capay Dam, with an 80 per cent conveyance system efficiency. -42- $700,000, exclusive of costs of rights of way. This cost is based on prices prevailing in the fall of 1954. Flood control benefits to lands abutting the shore of the lake are estimated to be greater than the cost of the enlargement, and such enlargement should therefore be considered as a separate project This enlargement would 1 have no effect on the yield of the projects considered in this report and for that reason, the cost was not considered in the evaluation and com- parison of costs and benefits from the projects proposed Wilson Valley Project The Wilson Valley Project consists of a dam and reservoir in Wilson Valley to regulate the waters of Cache Creek, provide irrigation water in Capay Valley and other portions of Yolo County, provide flood control to the land and structures located downstream from the reservoir, and enhance the recreational possibilities of Cache Creeko Wilson Valley Reservoir would be created by construction of a dam on the main stem of Cache Creek about 5 miles downstream from its confluence with the North Fork, or about 8 miles downstream from California State Highway Route 20 „ Several alternative dam sites were investigated in selecting the site for the Wilson Valley Dam„ The recommended site, referred to as the lower site, was selected as a result of foundation exploration, engineering design considerations, and economic analysis. The lower site is in the southeast quarter of Section 19, Township 13 North, Range 5 West, Mt. Diablo Base and Meridian, The stream bed elevation at the site is 867 feet, Wilson Valley is a reach of flat land extending along Cache Creek, downstream from, the mouth of Rocky Creek, for a distance of •43- about 2.5 miles. It is a remote area, accessible by a dirt road, extending southward from the Cache Creek crossing of California State Route 20, Wilson Valley, as well as the canyon of the North Fork of Cache Creek, would be completely inundated by a reservoir with a storage capacity of 1,000,000 acre-feet. Further, portions of California State Route 20 would require relocation. Storage capacities and corresponding surface areas of Wilson Valley Reservoir at various stages of water surface elevation are given in Table 6. TABLE 6 AREAS AND CAPACITIES OF WILSON VALLEY RESERVOIR "~~ water surrace ~T "~ Area, in "~~ T Capacity, in elevation, in feet g acres : acre-feet 867 880 20 100 920 200 3,^00 960 600 19,000 1,000 1,200 52,000 1,040 2,000 114,000 1,080 2,800 208,000 1,108 3,600 300,000 1,140 4,600 428,000 1,180 6,200 648,000 1,220 8,000 932,000 1,228 8,400 1,000,000 -44- Geologic Considerations Based on the findings of a dam site foundation exploration program, the Wilson Valley dam site is considered geologically suit- able for dams of the heights being considered. The geologic forma- tions found at the site area are sedimentary rocks of probable Upper Jurassic age,, unconsolidated deposits laid down in former lake beds and by stream action during the Plio-Pleistocene age, and Recent terrace and alluvial deposits. The terrace deposits are found to occur in the major por- tion of Wilson Valley, the only exception being the present channel area of Cache Creek. These deposits consist of well compacted light brown to tan silts underlain by coarse , gray-brown sandy and gravelly silts. The stream channel material is primarily highly pervious loose sand, gravel, and cobbles, bound in some zones by a matrix of red, sandy clay. General structural features of this region of the Coast Range are large complex folds, several miles in length and moderately narrow. The axes of the folds have a northwestward trend. Associated faults dip steeply and trend in the same direction. The general topography of this region consists of irregular hilly areas, in which the drainage is generally adjusted to the northwest structural trend. However, the stream pattern is complex, with many irregular gullies that enter the main stream channels more or less normal to its direction of flow. Most of the region, includ- ing the stream valleys, is now in a stage of early maturity. Several irregular flatbottom valleys, such as Wilson Valley, have developed within the area. -45- The foundation rock at the lower site, except for the stream channel deposits, consists entirely of lithologic units of the Khoxville group. The Khoxville units include, in decreasing order of occurrence, silty sandstones, siltstones, and silty shales. Veins of calcite or forms of calcium carbonate are present locally. The Khoxville beds strike across the channel and dip rather steeply upstream. The Recent alluvial deposits appearing in the Cache Creek channel at the dam site consist of highly pervious sand, gravel, and small cobbles. Both abutments consist of interlayered beds of Khoxville sandstones and siltstones with minor quantities of shales. The fractured nature of the material underlying the abutments would require only a moderate amount of grouting. Recent alluvial and stream channel deposits cover the chan- nel section to a maximum depth of 12 feet. Beneath the channel in this section the Khoxville formations are fractured for a depth of about 30 feet. Drill cores showed that these siltstones, sandstones, and shales in the channel were good foundation rock capable of sup- porting an earthfill dam when adequately grouted. No evidence of major faulting was apparent in the drill cores. The entire spillway area on the left abutment is underlain by mudstones, siltstones, and sandstones of the Khoxville group. An extensive trenching exploration was conducted to determine founda- tion conditions in the spillway area. The properties of the materials to be excavated from the spillway were determined with a view to pos- sible use in the dam embankment. As a result of laboratory analysis, it is estimated that an appreciable percentage of the excavated, mate- rial is suitable for use in the construction of the dam. -46- The topography of the spillway section is such that a con- siderable quantity of excavation will be required,, This can be reduced to a minimum, however, by the expedient of benching at regular vertical intervals , permitting the stabilization of the foundation material on a 1 to 1 slope. It will be necessary, in order to pre- vent erosion and undercutting of the foundation material, to line the entire spillway and provide for the installation of cutoff curtains . A detailed description of the geologic conditions of the Wilson Valley dam site and the location of possible construction materials can be found in Appendix C. Reservoir Capacity Considera tions As previously stated, estimates of costs and benefits for a Wilson Valley Reservoir with a storage capacity of about 300*000 acre-feet were made in order to compare the alternative Wilson Valley and Guinda Projects • This is approximately the same capacity as that established for the Guinda Reservoir proposed in the interim report of March, 1955 • In addition, estimates of cost and the benefits that would be derived were determined for a Wilson Valley Reservoir with capacities of 550,000, 830,000, and 1,000,000 acre-feet. The studies of the larger capacities were preliminary and were made primarily for the purpose of determing the capacity that would provide the maximum net benefit . Pertinent data for a reservoir at the Wilson Valley site comparable to the Guinda Reservoir, and for a reservoir that approaches the capacity which would yield the maximum net benefit, are presented in the following sections • -47- Wilson Valley Reservoir With Sto rage Cap acity of 300,000 Acr e-feet A Wilson Valley Reservoir with storage capacity of about 300, 000 acre-feet would provide a regulated supply of about 142, 000 acre-feet of water seasonally on a firm yield basis for use in Capay Valley and other portions of Yolo County . This amount of wa- ter released for beneficial uses includes both new yield and the presently utilized unregulated water supply reregulated to a firm yield basis. Through the use of surcharge storage the project would provide incidental flood control benefits, as a result of the re- duction of flood peaks downstream from the reservoir. It was estimated that a once-in-1, 000-year flood peak inflow would be re- duced from about 84, 000 second-feet to peak outflow of 63^ 000 second-feet. It was further estimated that a once-in-100-year flood peak would be reduced from about 60,000 second-feet to about 33*000 second-feet. The reservoir would provide a setting for the development of recreational facilities in the surrounding area, and would fa- cilitate the improvement of the stream flow of Cache Creek, downstream from the dam, for fish and wildlife purposes. The location of Wilson Valley Dam and Reservoir is shown on Plate 1, and its principal features are delineated on Plate 3. In consideration of results of geologic investigation of the dam site, a preliminary design for an earthfill dam was made to provide the basis for estimating the cost of a Wilson Valley Reser- voir with a storage capacity of 300,000 acre-feet. -48- General Features . The dam would have a height of 262 feet above stream bed., a crest length of 860 feet, a crest width of 30 feet, an upstream side slope of 3:1* and a downstream side slope of 2sl. It would contain an impervious core of compacted earth, with side slopes of 0o5:l° The core would be contained within upstream and downstream stability sections composed of stream bed gravels and material from spillway excavation. The total volume of em- bankment would be about 2,960,, 000 cubic yards, including 750,000 cubic yards of selected material in the impervious core. A concrete-lined side channel spillway would be constructed across the left abutment. The design discharge capacity would be 63*000 second-feet, with a maximum depth of water of 15 feet above the spillway lip. An additional 6 feet of freeboard would be pro- vided. The spillway design capacity was determined from a flood routing study based on flood frequency analyses of stream flow records . It was estimated that the design flood, would result from a runoff of 230 second-feet per square mile for the Clear Lake drain- age area, and 260 second-feet per square mile for drainage area below Clear Lake,, including that of the North Fork of Cache Creek. During construction of the dam, the stream would be di- verted through a 28-foot-diameter tunnel, about 1,150 feet in length, constructed through the right abutment. After completion of the dam, the tunnel would become a part of the outlet works releasing water into the stream channel. The inlet for the tunnel would consist of a sloping trashrack covering a transition structure providing access to the 28-foot-diameter tunnel. Two 60-inch-diameter steel pipes would be installed, extending from the outlet structure to a gate 49- chamber and tunnel plug located approximately on the axis of the dairu The gate chamber would contain two 4 x 4-foot pressure slide gates for controlling releases. The outlet structure would contain two 54-inch-diameter Howell-Bunger type valves, controlling releases made into a lined chute located near the downstream toe of the dam. The area that would be inundated by Wilson Valley Reser- voir is sparsely settled open range presently utilized for livestock grazing, About 10 miles of California State Highway Route 20 would require relocation. Pertinent data with respect to general features of Wilson Valley Reservoir, as designed for cost estimating purposes, are pre- sented in Table 7„ TABLE 7 GENERAL FEATURES OP WILSON VALLEY RESERVOIR WITH STORAGE CAPACITY OP 300,000 ACRE-FEET Dam 1 , V js. vT o © « e * c » o o 000 Acre-Feet Re-evaluation of the available water supply data for the purpose of determining the yield of reservoirs at the Wilson Valley site on Cache Creek indicated that the yield from Guinda Reservoir would be greater than heretofore estimated. The reservoir storage capacity at the Guinda site for both the current and previous reservoir yield studies was 303*000 acre-feet. The 1955 interim report Indicated that the firm seasonal irrigation yield of Guinda Reservoir, based on yield studies for the critical period from 1927 through 1935* would be 112,000 acre-feet, with a deficiency of not more than 35 per cent in any one year. In addition, a firm seasonal supply of 19*000 acre-feet was provided in the yield studies for release to the Cache Creek channel below Guinda dam site for ground water recharge. Thus, the previously -62- estimated total firm yield of Guinda Reservoir was about 131 .,000 acre-feet per seasoru Deficiencies in the irrigation supply were estimated to be 35 per cent in 1933 and 27 per cent in 1934. Re-evaluation of the yield studies of Guinda Reservoir during the current investigation indicated that the average seasonal release from the reservoir, not including spill., would be 172,500 acre-feet during the 45-year period from 1911-12 through 1955-56 , It was estimated that of this release an average of 14,500 acre-feet per season would be lost by percolation from the stream channel between Guinda Dam and the Moore and Capay diversion dams. The resulting firm seasonal yield of Guinda Reservoir at the diversion points would be 158,, 000 acre-feet, with a deficiency in only one year of the 45-year period. This deficiency would have occurred in 1934, amounting to about 50 per cent of the firm yield. This deficiency, although sizeable in quantity, is less than has occurred historically. For example, in 1947 a 75 per cent deficiency from the average supply was experienced on Cache Creek. On the other hand, the regulated yield would permit a greater quantity to be diverted seasonally for beneficial uses in the service area than would be available without such regulation. In' both studies discussed above, the estimates of firm supply include both new yield and the presently used unregulated water supply. The location of Guinda Dam and Reservoir is shown on Plate 1, and its principal features are delineated on Plate 5« General Features . The dam would be an earthfill structure, 170 feet in height from stream bed to crest., and would have a crest length of 8,000 feet. The crest width would be 20 feet, with up- stream slopes varying from 2sl to 3°5»1* and downstream slopes -63- varying from 2:1, 3 si* to 3- 5 si. The crest elevation would be 520 feet. The dam would be constructed with a central core of compacted selected impervious material placed symmetrically about the dam axis, with a top width of 10 feet and side slopes of 0.5 si. The core would extend into a cut-off trench excavated through the unconsol- idated terrace deposits. The cut-off trench would have a bottom width of 30 feet and sides slopes of 1.5 to 1, with depths as great as 50 feet in some locations. The upstream and downstream exterior sections of the dam would be compacted random fill obtained from the local terrace and gravel deposits. The downstream section would be provided with gravel drains. The upstream face would be protected from erosion and wave wash by a 3- foot facing of rock riprap. The volume of embankment would be about 15,600,000 cubic yards, including 2,700,000 cubic yards of selected impervious material in the core. The spillway would be located through a saddle just east of the left abutment. The original design discharge capacity of about 40,000 second-feet has been revised on the basis of data now available, to about 70,000 second- feet. This would increase the cost of the spillway, over that previously estimated in the report of March, 1955. However, the cost used herein has not been revised, as redesign of the Guinda Project was not authorized in the current investigation. Outlet works would consist of a 90-inch-diameter steel pipe, encased in concrete, through the left abutment. The submerged inlet to the pipe would be equipped with suitable trashracks and a hydraulically controlled slide gate. Irrigation releases of water -64- would be controlled by a Howell-Bunger type valve at the downstream end. The outlet pipe would be utilized for diversion of stream flow during construction. The area flooded by Guinda Reservoir includes a well- developed portion of the upper end of Capay Valley. The reservoir would cover the entire upper valley floor as well as the lower slopes of the bordering hills, and would have an area of 3,820 acres at maxi- mum water surface. Most of the area is cultivated, and a large portion is ir- rigated. Almonds are the predominant crop in the reservoir area, covering about 30 per cent of the valley floor. Other agricultural developments include field crops, grain crops, and livestock. The portion of State Highway Route 16 that extends through the reservoir area would have to be replaced with about 6 miles of two-lane highway. About 5 miles of unpaved roads would be required to replace county roads that would be inundated. Other public utilities to be replaced would include 11 miles of electric power transmission lines and 11 miles of telephone lines. The general features of Guinda Dam and Reservoir are shown in Table 15. Costs . The capital cost of Guinda Reservoir with a storage capacity of 303,000 acre-feet was estimated to be about $18,065,000, and the corresponding annual costs, using an interest rate of 4 per cent per annum and an amortization period of 50 years, were estimated to be about $936,000. A detailed cost estimate is presented in Ap- pendix B. A summary of capital and annual costs for Guinda Dam and Reservoir Project is presented in Table 16. ■65- TABLE 15 GENERAL FEATURES OF GUINDA RESERVOIR Dam X y J^J " «oceoe«e«oooooooe< Crest elevation, in feet ••••••«-. Crest lengthy in feet ••••••••», Crest width, in feet •••»••••*, Height above stream bed, in feet . . e , Freeboard above spillway lip, in feet . , Side slopes Downstream »••»••••••••••, Elevation of stream bed, in feet . . . , Volume of fill, in cubic yards ••»•••• Reservoir Surface area at spillway lip, in acres . . „ Storage capacity at spillway lip, in acre-feet Drainage area, in square miles ••••••• Average seasonal runoff, in acre-feet . . . , Seasonal yield, in acre-feet . . . ..... . Type of spillway .............. Spillway discharge capacity, in second feet . Type of conservation outlet works ...... o o o o o o o o C~ci i. L'l i 1 J — i — L ooeooooe ^) C\) ce«ooo«o OjUUU «oooeeoo C\) eooo«co« J_ ( w eooeeeeo -L U o « (variable) 2:1, 3.5:1 (variable) 2:1, 3:1, 3.5:1 ..... o . .15.600,000 Type of flood control outlet works > o e ♦ o » ^j OL/U ...... 303,000 ecoooeeo ^7 J/ £- ........ 456,000 ........ 158,000 . . . lined chute across left abutment ........ 40,000 . .90-inch-diameter steel pipe beneath dam 22 by 75-foot submergible radial gate in spillway TABLE 16 SUMMARY OF ESTIMATED COSTS OF GUINDA PROJECT WITH RESERVOIR STORAGE CAPACITY OF 303,000 ACRE-FEET (Based on prices prevailing in fall of 1957) Item Dam and appurtenances Lands, easements, rights of way, and clearing Relocation of public utilities Interest and capital recovery Operation, maintenance, replace- ment, and general expense TOTALS Capital costs : Annual costs $12,760,000 4,400,000 905,000 $18,065,000 $ 841,000 95,000 $936,000 -66- Primary Benefits, Benefits from construction and operation of the Guinda Project would accrue from the regulation of water for irrigation use., from incidental flood protection to downstream areas., and from recreational enhancement . As previously indicated., recreational benefits that would accrue from this project were not evaluated* Furthermore., analysis of the magnitude of probable flood control benefits indicated that provision of flood control storage space in a reservoir of this ca- pacity would not be economically justified. However, operation of the reservoir without specific flood control features would provide inci- dental flood control benefits. These incidental benefits were not evaluated in monetary terms ^ and the economic justification of the Guinda Project was based solely on the resulting irrigation benefits. The irrigation benefits would consist of the increase in long-term average net farm income that would be realized from appli- cation of project water. An estimate of the total average annual net farm income resulting from the regulation of water in Guinda Res- ervoir is presented in Table 17 « As previously demonstrated, the average annual net farm income , under preproject conditions, was estimated to be $2,030,000. Deducting this amount from the average annual net farm income of §^, 793,000 (Table 17), the average annual irrigation benefit would amount to $2,763,000 at the farm head gate. Benefit-Cost Ratio . The ratio of irrigation benefits to project costs for the Guinda Project would be 2.c to 1. . -67- TABLE 17 ESTIMATED AVERAGE ANNUAL NET FARM INCOME IN PROJECT AREA WITH 303,000 ACRE-FOOT CAPACITY RESERVOIR AT GUINDA Area Land utilization and crop pattern Per : Acres cent: Seasonal farm delivery Annual net farm income : Acre -feet: Total, ;Per acre,: Total, : per : in 1 in : in : acre :acre-feet: dollars : dollars Irrigated Land Field crops Alfalfa Sugar "beets Beans, milo, corn Pasture Subtotals Truck crops Tomatoes Melons - Others Subtotals Orchards Almonds Apricots Prunes Walnuts, peaches Subtotals Fallow (dry-farmed grain) Subtotals Subtotals, Irrigated Land Dry-farmed Land Field crops Small grains Pasture Others Subtotals Orchards Almonds Others Subtotals Fallow Subtotals Subtotals, Dry-farmed Land Native Vegetation Subtotals, Native Vegetation TOTALS, PROJECT AREA 3.fc 6.8 l.k 3-k 5,4oo 10,800 2,200 5,400 "237BOO 4.8 7,600 1.0 1,500 ^9 1,500 10, t 4.1 •7 .7 l.k 6.9 4.7 T7f- 6,500 1,100 1,100 2,200 10,900 7,600 "TV^oo 33.3 52,900 33.8 53,6oo 12.8 20,300 .6 1,000 47.2 7^,900 1.8 2,800 .1 200 1.9 3,000 9.4 14,900 9.4 14,900 58.5 92,800 8.2 13,000 8.2 13,000 100.0 158,700 3-5 2.4 2.1 4.3 2.7 2.1 2.1 2.0 2.7 2.7 3.3 19,000 26,000 5,000 23,000 73,000 21,000 3,000 3,000 27,000 13,000 3,000 7,000 4,000 26,000 126,000 46 73 29 31 106 80 80 178 185 110 175 19 6 4 4 12 13 126,000* 248,000 788,000 64,000 168,000 1,268,000 806,000 120,000 120,000 1,046,000 1,157,000 203,000 121,000 385,000 1,866,000 144,000 144,000 4,324,000 322,000 81,000 4,000 407,000 33,000 3,000 36,000 443,000 26,000 26,000 4,793,000 * Estimated quantity of water delivered at farm head gates, based on average annual diversion of 158,000 acre-feet at Capay Dam, with an 80 per cent conveyance system efficiency. -68- CHAPTER IV. COMPARISON OP WILSON VALLEY AND GUINDA PROJECTS The comparison of engineering and economic feasibility of the alternative Wilson Valley and Guinda Projects, as required by Section 12663 of the Water Code, was made after engineering, geologic, and economic studies had determined accomplishments of a project at Wilson Valley with a storage capacity of about 300,000 acre-feet, equivalent to that of the Guinda Project. In addition to this com- parison, studies were made to determine the size of reservoir at the Wilson Valley site resulting in maximum net benefits when operated under present conditions of upstream development. It was found that such a project would have a storage capacity of about 1,000,000 acre- feet. The use of the term "economic feasibility" in the authoriz- ing legislation was construed to refer to the relationship between costs incurred in, and the benefits which are derived from construc- tion and operation of a water development project. This relationship is commonly termed "benefit-cost ratio", and such terminology has been used in this report. The comparison of the alternative projects is presented under the general headings of "Engineering Feasibility" and> "Economic Feasibility" . Engineering Feasibility Studies conducted during this investigation indicated that both the Wilson Valley and Guinda Projects possess engineering feasi- bility. It was determined that water supplies for the projects are adequate in quantity and quality; the sites for the dams, reservoirs, and other facilities are geologically suitable; the projects can be -69- built with available materials and present techniques at a reasonable cost; and the proposed structures can be properly designed and be functionally sufficient. However , before a final decision is made on the project to be developed, further consideration should be given to an evaluation of alternative reservoir operation criteria, reservation of water for upstream use, and the possibility of the conjunctive development of both ground water and surface water storage. The engineering feasibilities of the Wilson Valley and Guinda Projects were compared by relating the general features and estimated costs of the two projects. General Project Features A comparison of the general features of the alternative projects is presented in Table 18. Project Costs The capital costs of the Wilson Valley Project, with and without a reservation of storage for flood control purposes, for a range of reservoir storage cpacities up to 1,000,000 acre-feet are shown in Figure 1 of Plate 6. The capital cost of the Guinda Project with a storage capacity of 303,000 acre-feet is also shown. Cor- responding annual costs are shown in Figure 2 of Plate 6. A comparison of the estimated costs of the alternative projects is given in Table 19- Economic Feasibility Studies conducted during this investigation indicated that each of the alternative Wilson Valley and Guinda Projects is economically feasible. It was shown that each project would result -70- TABLE 18 COMPARISON OF GENERAL FEATURES OF WILSON VALLEY AND GUINDA PROJECTS : Wilson Valley Project : Guinda Project Item : Reservoir storage 1 capacity of :1, 000, 000 acre -feet ^Reservoir storage : capacity of ,300,000 acre-feet ^Reservoir storage : capacity of : 303, 000 acre-feet Flood control reservation, in acre -feet 65,000 Type of dam Earthfill Earthfill Earthfill Height of dam, in feet 377 262 170 Crest length, in feet 1,3^0 860 8,000 Crest elevation, in feet 1,244 1,129 520 Volume of fill, in cubic yards 8,600,000 2,960,000 15,600,000 Normal pool elevation, in feet 1,238 1,123 510 Normal pool area, in acres 8,400 3,600 3,800 Dead storage, in acre-feet 3,000 3,000 3,000 Type of spillway Side channel Side channel chute Estimated average seasonal runoff, in acre -feet 372,000 372,000 456,000 Estimated firm seasonal yield, in acre-feet 252,000 142,000 158,000 ■71' to +3 to o O o O o o o -p a o o o CD »\ »N •\ CD H H LTN VO ft 1 cd 3 -d- CO ON CO ON CD § •*£- ■m- !m a cd o <; tj 0} 3 to •H O -p o O o o 3 O to o o o o o o o o o o o o oo o o ltn LT\ o rH VO o O VO on cd -p •H CO J- *N -d- on o 00 CO ft H H EH cd -&■ H»- o q 1 to o p K to O o o ft P o a O o o o o o O cd 3 3 < CO <^ o O O P o o o O W O to o o o O >H H H O o o o o O H •H -v o *\ *\ "\ *\ i_j cd ts o o o o o (— i ft O 1-1 VO CO On oo < PO 03 t- CO ON VO > •H s o LTN § ft H H o bJD cd -€Q- Hft- ON H •H H to 3 ts •H cd S o o o o O o pq fe > o o o o < o 0) cj •\ •\ •N Eh u -P o o o CO ft (L) H t— ON VO EH CD cd -d- H • VO CO to >s Cm 3 *N «\ O 0) cd to p o o o o g £ a o to o o o o o o o o o o o o M to O o •\ *\ *\ •s EH ti H * o o o o CO •H O H c- on ON ON w co ^ o cd LfN o ON LTN gj o ■P *\ *\ ■s •\ fe PQ •\ ■H on OJ LTN H o v — ' H cd -€£- m -tB- g o O • c O o o m CO CD H £ co a CD § cd CO ft £ CD !>> X o •H ^ CO ft O to P> bfl P •H H •H P 3 0) > o o CD u H cd M •> cd -p CD p ft cd d M p o o EH td o P to •H cd O !-H «\ cd CD P H ft Co to 'd TH £ o o CD cd ft s a cd H P CD u cd Q a (D & •72- in substantial benefits in excess of project costs. However, before a final decision is made on the project to be developed, the recre- ational benefits that would accrue to the projects should be evalu- ated in monetary terras. In the following sections the economic feasibilities of the Wilson Valley and Guinda Projects are compared by, first, examin- ing the accomplishments of the projects, from which the benefits would be derived, and second, by examining the benefits that would accrue from such accomplishments. Project Accomplishments The firm seasonal yield of the Wilson Valley Project, with and without a reservation of storage for flood control purposes, for a range of reservoir storage capacities up to 1,000,000 acre-feet, is shown in Figure 3 of Plate 6. The firm seasonal yield of the Guinda Project for a reservoir storage capacity of 303^000 acre-feet is also shown . A comparison of the accomplishments of the alternative projects, together with the existing preproject conditions, is pre- sented in Table 20„ Project Benefits The benefits that would accrue from the Wilson Valley Proj- ect, with and without a reservation of storage for flood control purposes, for a range of reservoir storage capacities up to 1,000,000 acre-feet, are presented in Figure 4 of Plate 6. The benefits that would accrue from the Guinda Project with a reservoir storage capac- ity of 303,000 acre-feet are also shown in Figure 4. -73- CO EH % o g 3 c3 CO EH CO M & 6 o Pw o § CO H 5 o -P 4J cD o5 a) ^ 'h 'h •i-3 « O -p £ CO r>s U -p - H -H a} o3 •H O «d cd O Pi > ftO •H hllO 3 H O w 0O a> K ^ -P bO oS U i U\ -P -p M -H 0$ •H O O aJ O [■^3 > ft O O !h (SO £ O ^ ra |>a K 00 • • * a • H -P H S3 bO > aj ft fn ft i a OO0 -P U CQ 01 >) H -P o3 •H U -H rs •H O O O a3 O > PhO m o3 *^ 0OO ra O O «. H -P w a "-3 -H O -P U -H ft CO vo LfA (VI H H O O O O O O O O O •\ •s •> LT\ 0J OJ VO LT\ O CM CM o o o UA o H -P ft 1 u u a H •H J»s H a a o ra cd W *H •H ft «3 •P a3 •P ra W o o o UA CO 0$ -P ft fn O c3 a •H >5 H > •H H 'd S in c3 ft O O oaco t- *\ •\ »\ *v CM 0J 00 CO lt\ a LT\ H O O CM O O O O O *\ *\ •\ •N LfA O H 00 VO CM 0O UA VO t- *\ «S -4- -eo- CM -eo- -p o •m o 000 o 000 o O f- o c— •\ *\ *\ *\ 440 CO CO VO H LTN H OOO O OOO O LAW O t— *\ »\ »\ *\ LT\ OA-4" CO CM H H ua H H ra *H o a3 Pi ra -h O -P o3 O -p o O u ft >>. -p 03 W •H ?H (H •H ^3 S -o •H O ?H •» ft -P o fl -H O nrf ?h a ft o3 H •H CJ O t3 -h C -P a3 oi H -P S > £h 03 a ^ o3 oi *H oi -P o •i-D o u ft rH 03 -P O +3 s CO o o CM LfN O -P o a -P ■HQ ch ra a *h o ^ o3 o > Ti S ^H O tH -h ra ra CO u o Si o o3 o 03 OJ u 0$ ra w O u o o o o o 00 o CM o •H B fi 0$ -d d o 'd o o H O Ch H 'd -p 1 ■H -P ra -p -p s s O O O OOO OOO t-o CM O O G\ O O O »\ •\ *\ »N "\ •\ •\ •s *\ »y ^ •N CM H H H CO vo -d- -=$■ 0\ r-i CO L(A H LfA O H vo CM O CO en "\ -4- -ee- O tr\ 00 CM -ee- CO VO en o o o UA H o o o o VO 03 >> o o H 1 a •H I O o .a -p •H +^ CH i -d Pl o o bO !4 ra oJ ^ £3 O "H ra •h -d d O d O H O ch H Ph ra ra w o H o PJ o3 ^ > a o o •p Pi o ^H ft o CM W w H ■d H •h >> 03 a o ra o3 ra S CM U •h Ch H 03 Eh ra rH 03 Pi cr pq CO 1 1 o3 P -74" The excess of benefits over project costs, that would accrue from the Wilson Valley Project, with and without a reservation of storage for flood control purposes, for a range of reservoir stor- age capacities up to 1,000,000 acre-feet, is presented in Figure 6 of Plate 6, together with equivalent values for the Guinda Project with a reservoir storage capacity of 303,000 acre-feet. Data from the studies resulting in this curve were used in selecting the reser- voir storage capacity at Wilson Valley which would provide maximum net benefits. Benefit-Cost Ratio The benefit-cost ratios for the Wilson Valley Project, with and without flood control reservation, for a range of reservoir stor- age capacities up to 1,000,000 acre-feet, and for the Guinda Project with a reservoir storage capacity of 303,000 acre-feet, are shown in Figure 5 of Plate 6. A comparison of the estimated costs and benefits that would result from construction of one of the alternative projects is given in Table 21. •75- TABLE 21 COMPARISON OF ESTIMATED BENEFITS AND COSTS OF WILSON VALLEY AND GUINDA PROJECTS Function Wilson Valley Project : Reservoir storage ^Reservoir storage : capacity of : capacity of ! 1 i 000,000 acre-feet; 300, 000 acre-feet Guinda Project Reservoir storage Capacity of 303,000 acre-feet Annual Benefits Firm seasonal yield, in acre-feet Irrigation Flood control Recreation Approximate total annual "benefit (except recreation) 252,000 $ 5,255,000 160,000 high $ 5,^15,000 1^2,000 $ 2,350,000 incidental high 158,000 $ 2,765,000 incidental moderate $ 2,350,000 $ 2,765,000 Costs Capital Annual Benefit-Cost Ratio* * ( annual benefit) ( annual cost ) $ 31,590,000 $ 1,660,000 3.2:1 $ 17,630,000 $ 91^,000 2,6:1 $ 18,065,000 $ 936,000 2.9:1 -76- CHAPTER V. CONCLUSIONS AND RECOMMENDATIONS This chapter contains pertinent conclusions resulting from the investigation to compare Wilson Valley and Guinda Reservoirs. Recommendations are also presented for appropriate action by those interested in the construction of a water development project on Cache Creek. Conclusions The engineering, geologic , and economic surveys and studies conducted during this and prior investigations, have resulted in the f ollowing conclusions : 1. The unreliability of the water supply presently availa- ble for irrigation use in the Cache Creek Service Area, and the pos- sibilities for expansion of irrigated agriculture if adequate water can be made available, create a current need for the development of additional water conservation facilities in the Cache Creek Basin. 2. The construction of either Guinda or Wilson Valley Reser- voir would provide the needed regulation for conservation. Guinda Reservoir constructed to a capacity of 303^000 acre-feet would re- regulate the flows of Cache Creek to provide a total firm seasonal yield of 158,000 acre-feet. Wilson Valley Reservoir constructed to a capacity of 300,000 acre-feet would provide a total firm seasonal yield of 142,000 acre-feet. Wilson Valley Reservoir would provide in- creasing net benefits with increases in storage to a maximum storage capacity of about 1,000,000 acre-feet. If constructed to a storage capacity of 1,000,000 acre-feet, the total firm seasonal yield from the project would be 252,000 acre-feet 3. During the winter and spring of 1958, flood conditions around Clear Lake in Lake County and the overtopping of levees along -77- Cache Creek in Yolo County have again emphasized the prevailing flood threat to both counties and the need for the construction of facilities to protect against flood damage. 4. Either the Wilson Valley or the Guinda Project would have a substantial beneficial effect on the control of floods in Cache Creek and on reduction of flood damage in the Cache Creek Serv- ice Area. 5. Either the Wilson Valley or the Guinda Project would have a substantial beneficial effect on the control of flood condi- tions in the areas adjacent to Clear Lake, provided the outlet channel from the lake were enlarged. The construction of a reservoir on the main stem of Cache Creek probably would eliminate the opposition of downstream interests in Yolo County to modification of the Bemmerly Decree , and thereby permit the enlargement of the outlet channel from Clear Lake. 6. Costs of the projects discussed in this project are esti- mated to be i Capital cost Annual cost Wilson Valley Project 300,000 acre-foot storage capacity $ 17,600,000 $ 917,000 1,000,000 acre-foot storage capacity 31,600,000 1,660,000 Guinda Project 303,000 acre-foot storage capacity $ 18,100,000 $ 936,000 Costs of Wilson Valley Projects were based on prices pre- vailing in the fall of 1957, and those of Guinda Project were based on a modification of costs as of the fall of 195^ to reflect 1957 price levels. 78- 7. Total annual project benefits were estimated to be: Wil son Valley Project 300,000 acre-foot storage capacity $ 2,400,000 1,000,000 acre-foot storage capacity 5,400,000 Guinda Project 303,000 acre-foot storage capacity $ 2,800,000 8. The further development and use of water in the basin above the Wilson Valley or Guinda Projects would deplete yields of the projects in the amount of the increase in water consumptively used upstream. 9. Either the Wilson Valley Project or the Guinda Project would provide an opportunity for the development of recreational facilities . 10. Either of the considered projects could be operated under plans whereby the fluctuation of Clear Lake would be kept to a minimum, except during critically dry periods, and all releases for downstream use would be made from the storage reservoir on the main stem of Cache Creek. Such plans of operation, however, would to some extent adversely affect reservoir recreation possibilities. 11. Both the Wilson Valley and Guinda Projects with reser- voir storage capacities of about 300,000 acre-feet possess engineer- ing and economic feasibility. 12. From an economic comparison of the alternative projects it is indicated that with a storage capacity of about 300,000 acre- feet, the Guinda Project with a benefit-cost ratio of 2.9 to 1 would have slightly greater economic feasibility than would the comparable Wilson Valley Project with a benefit-cost ratio of 2.6 to 1. The costs of Guinda Reservoir used in this comparison, however, do not reflect the increased costs of spillway construction and highway -79- relocation that have been determined to be necessary since the publi- cation of the first interim- report ; in accordance with the legislative instructions and restrictions 3ontained in Chapter 1950, Statutes of 1955; these increases in costs have not been evaluated. 13. The Wilson Valley Project, with reservoir storage capac- ities up to about 1,000,000 acre-feet, possesses engineering and economic feasibility. The project that would result in the maximum net benefits would involve a reservoir storage capacity of about 1,000,000 acre-feet ; studies indicate that it would have a benefit- cost ratio of 3-2 to 1. 14. The lower Wilson Valley dam site is better from an engineering and geologic standpoint than the upper Wilson Valley site, due to better foundation conditions. 15. Although specific studies of Guinda Dam were not made during the current investigation, present geologic knowledge of foundation conditions of the site indicates that the Guinda Project, with a storage capacity of any appreciable amount in excess of 303,000 acre-feet, would not be engineeringly feasible. 16. The final choice between the alternative reservoir sites should include consideration of the adverse effects on the future economy of the State occurring from the permanent loss of the otherwise irrigable land submerged in the reservoir. Recommendations As a result of the engineering, geologic, and economic studies reported on herein, it is recommended: 1. That no further consideration be given to the Guinda Project for the development of the waters of Cache Creek. -80' 2o That the Wilson Valley Project be authorized as the next water conservation project on Cache Creek, and that the reservoir storage capacity be of such amount that the project would derive the maximum net benefits. 3. That an investigation be conducted to determine the financial feasiblity of the Wilson Valley Project that would return the maximum net benefits . 4. That in developing financial feasiblity of the Wilson Valley Project , consideration be given to conjunctive operation of the project with the ground water basin in the project service area, to depletion resulting from upstream uses, to other possible water conservation developments in the Cache Creek Basin, and to a coordi- nated flood control operation of the reservoir with Clear Lake. -81- APPENDIX A RESERVOIR YIELD STUDIES A-l TABLE OF CONTENTS Page Seasonal Summary of Monthly Yield Study, Seasonal Summary of Monthly Yield Study, Wilson Valley Reservoir With 300,000 Acre-Foot Storage Capacity ....... . • . A-8 Seasonal Summary of Monthly Yield Study, Wilson Valley Reservoir With 1,000,000 Acre-Foot Storage Capacity ........ . .... . . . . A-9 Seasonal Summary of Monthly Yield Study, (jrUino.a .Keservoir .««.«.«.*«.«••.*«.».« e A— lvJ A-2 Summary of Reservoir Yield Study Procedures and Criteria Presented in this appendix are seasonal summaries of monthly yield studies of Clear Lake, Wilson Valley Reservoir for 300,000 acre- foot and 1,000,000 acre-foot capacity, and Guinda Reservoir for 303,000 acre-foot storage capacity . The objective of these studies was to determine the water supply that would be available at the Moore and Capay Diversion Dams under preproject and project conditions, The general procedure included: 1. Compilation and analysis of all pertinent hydrologic data. 2. A monthly yield study of Clear Lake to determine the theo- retical inflow to the lake for the average period 1911-12 to 1955-56 with the present level of v/ater use throughout that period,, assuming an enlarged outlet channel of 8,500 second- foot capacity, and using the storage and release criteria established by the Gopcevic Decree . 3. A monthly yield study of Clear Lake using the above- estimated theoretical inflow to the lake to determine theo- retical releases and spills from the lake for the mean period under the criteria stated in the above step. A sum- mary of this study is presented in tnis appendix, 4. Monthly yield studies of the previously proposed Guinda Reser- voir and four sizes of reservoirs at Wilson Valley using the theoretical releases and spills from Clear Lake, and esti- mated inflow from the remaining tributary area to determine the firm yield available to the project service area at the diversion point. Seasonal summaries of studies for reser- voirs at Wilson Valley with storage capacities of 300,000 A-3 and 1,000,000 acre-feet and for Guinda Reservoir with a storage capacity of 300,000 acre-feet are presented in this appendix. Discussion of the various items included in the reservoir yield studies is presented "below. C lear Lake Yield Study 1. Inflow to Clear Lake represents the theoretical Inflow that would occur with present level of water use development im- posed upon historical water supply data for Clear Lake. This was determined in a yield study in which the lake was operated within the limits of the Gopcevic Decree. It was also assumed that the lake outlet was enlarged to 8,500 second-foot capacity. 2. Clear Lake storage on April 1, as shown, was used to estab- lish theoretical releases as required by the Gopcevic Decree and estimated inflow. Elevations shown refer to the Rumsey gage. 3. Unit water surface evaporation was based upon records of evaporation at East Park Reservoir on Stony Creek. 4. The area of Clear Lake and the storage capacity at various water stages were based upon data obtained from the United States Bureau of Reclamation. 5. The seasonal release from Clear Lake was based on criteria developed from the relationship between historical diver- sions at Moore and Capay Dams and the April 1 water stage of Clear Lake. The seasonal release thus determined was pro- portioned on a monthly schedule approximating present practice A-4 and altered to reflect estimated downstream losses or gains to produce the required monthly release at Clear Lake, 6. Spill from Clear Lake represents water discharged from the lake to prevent the water stage from exceeding eleva- tion 7.56 on the Rumsey gage. Wilson Valley Reservoir Yield Study 1. Inflow to Wilson Valley Reservoir is comprised of spills and releases from Clear Lake as determined from the above yield study,, and inflow from the area tributary to Cache Creek below Clear Lake Dam including the North Fork of Cache Creek, 2. Unit water surface evaporation was based upon records of evaporation at East Park Reservoir on Stony Creek. 3. Areas of the reservoir and storage capacities at various stages were determined from reservoir topographic maps prepared by the United States Bureau of Reclamation. These were supplemented by recent United States Geological Survey quadrangles . 4. Releases from the reservoir were made in amounts that would provide a firm seasonal yield on a monthly irrigation schedule at the Moore Ditch and Capay Dam diversion points. 5. Spill from Wilson Valley Reservoir represents discharge over the spillway or releases through the flood control outlet to maintain the reservoir storage within operating limits. A-5 Guinda Reservoir Yield Study 1. All yield study procedures and criteria for Guinda Reser- voir were the same as those for Wilson Valley. 2. Additional runoff occurring between the two dam sites was added to the inflow to Wilson Valley to determine the in- flow to Guinda Reservoir. 3. The area of Guinda Reservoir and the storage capacity at various water stages were based upon data prepared by the former Division of Water Resources . A-6 SEASONAL SUMMARY OP MONTHLY YIELD STUDY CLEAR LAKE (In acre-feet) Active storage capacity: 314,000 acre-feet :Gage height : Yield at Inflow :on April 1, Release : points of Season to Storage, Evapo- : in feet Spill from :diversion, Clear Lake* October 1 ration : on :Rumsey gage Clear Lake :preproject : conditions 1911-12 209,700 354,900 207,600 3.21 9,700 3,700 1,300 13 297,000 343,600 216,500 5.08 20,700 77,800 88,000 14 873,400 325,600 227,100 7.56 465,700 151,600 164,500 15 762,300 354,600 200,900 7.56 411,900 145,600 164,500 1915-16 492,900 358,500 219,100 7.56 141,200 151,500 164,500 17 305,000 339,600 209,000 5.82 18,400 117,600 123,500 18 205,700 299,600 216,100 2.15 2,600 19 366,200 286,600 212,300 5.80 11,400 113,600 122,800 20 118,500 315,500 202,200 O.58 21,500 1,200 1920-21 633,700 209,100 201,400 7.56 120,700 152,600 164,500 22 318,400 368,100 218,400 6.15 13,700 127,700 139,000 23 339,000 326,700 224,400 4.87 32,000 72,000 79,000 24 140,100 337,300 238,500 1.68 100 25 515,100 238,800 184,100 6.25 96,200 122,600 143,500 1925-26 335,600 351,000 180,100 5.66 82,400 107,600 116,000 27 771,700 316,500 194,100 7.56 382,400 152,000 164,500 28 429,000 359,700 204,300 7.56 80,800 154,200 164,500 29 167,900 349,400 206,500 2.77 1,400 1,400 30 363,500 308,000 197,900 6.05 17,500 123,100 134,000 1930-31 134,400 333,000 224,000 1.42 1,500 32 286,300 241,900 207,200 3.11 3,800 33 194,300 317,200 208,900 2.82 3,900 34 254,200 298,700 206,300 3.78 4,300 22,200 28,300 35 422,900 320,100 189,300 7.12 73,400 153,900 164,500 1935-36 425,900 326,400 195,600 7.56 37,600 152,700 164,500 37 314,000 366,200 199,400 6.46 17,500 144,500 153,300 38 789,800 318,800 186,300 7.56 408,500 153,400 164,500 39 152,500 360,400 203,100 3.22 6,400 2,000 40 598,900 303,400 193,600 7.56 204,800 151,800 164,500 1940-41 889,700 352,100 188,600 7.56 543,700 150,600 164,500 42 749,200 358,900 192,200 7.56 389,000 148,300 164,500 43 523,700 378,600 200,500 7.56 175,600 157,800 164,500 44 229,600 368,400 185,300 5.10 7,900 82,200 90,000 45 306,800 322,600 189,600 5.86 11,700 123,200 125,700 1945-46 411,700 304,900 192,400 7.56 37,900 155,700 164,500 47 209,800 330,600 197,400 3.64 11,800 21,300 21,500 48 267,100 309,900 157,500 2.18 129,500 300 49 361,400 289,700 254,600 5.22 4,400 89,500 90,000 50 360,300 302,600 293,800 4.22 21,300 43,900 48,300 1950-51 594,600 303,900 271,700 7.56 129,100 141,800 164,500 52 723,000 355,900 266,800 7.56 309,800 147,100 164,500 53 590,500 355,200 263,800 7.56 174,800 143,500 164,500 54. 460,400 363,600 254,600 7.56 67,900 150,100 164,500 55 248,400 351,400 216,000 4.05 36,400 32,600 41,000 1955-56 867,400 314,800 217,100 7.56 462,500 147,700 164,500 Average 422,500 326,500 211,500 5.56 115,500 95,500 103,800 * Estimated inflow to Clear Lake, assuming present conditions of water use development prevailed throughout the study period. A -7 SEASONAL SUMMARY OP MONTHLY YIELD STUDY WILSON VALLEY RESERVOIR WITH 300,000 ACRE-FOOT STORAGE CAPACITY (In acre-feet) Seasonal yield: 142.000 acre-feet Season Inflow to Wilson Valley Reservoir Without flood control storage reservation Cache Creek: Spill from: Irrigation below : Clear : release from: Clear Lake*: Lake : Clear Lake : Total Storage, October 1 Evaporation Spill Yield Release : at from : point of reservoir: diversion 1911-12 35,700 9,700 3,700 49,100 300,000 8,000 31,500 139,700 142,000 13 60,300 20,700 77,800 158,800 169,900 7,000 132,500 142,000 14 423,600 465,700 151,600 1,040,900 189,200 10,700 772,400 147,000 142,000 15 334,300 411,900 145,600 891,800 300,000 9,500 715,600 166,700 142,000 1915-16 321,500 141,200 151,500 614,200 300,000 10,500 454,700 149,000 142,000 17 127,000 18,400 117,600 263,000 300,000 9,900 134,500 144,600 142,000 18 48,700 2,600 51,300 274,000 9,400 14,400 140,600 142,000 19 142,900 11,400 113,600 267,900 160,900 9,600 4,900 141,200 142,000 20 29,500 21,500 1,200 52,200 273,100 9,000 14,800 142,600 142,000 1920-21 222,400 120,700 152,600 495,700 158,900 9,700 198,200 146,700 142,000 22 103,700 13,700 127,700 245,100 300,000 11,100 107,300 138,600 142,000 23 125,300 32,000 72,000 229,300 288,100 9,300 134,100 141,800 142,000 24 26,300 100 26,400 232,200 10,900 140,800 142,000 25 154,100 96,200 122,600 372,900 107,700 6,500 43,100 136,000 142,000 1925-26 154,300 82,400 107,600 344,300 295,000 8,300 201,300 161,300 142,000 27 242,000 382,400 152,000 776,400 268,400 8,900 586,000 149,900 142,000 28 139,400 80,800 154,200 374,400 300,000 10,200 219,400 139,800 142,000 29 37,900 1,400 1,400 40,700 300,000 9,700 '28,200 143,100 142,000 30 148,300 17,500 123,100 288,900 159,700 10,200 11,500 143,300 142,000 1930-31 16,600 1,500 18,100 283,600 9,000 134,100 142,000 32 87,500 3,800 91,300 158,600 7,500 138,800 142,000 33 43,000 3,900 46,900 102,900 4,700 142,300 142,000 34 53,500 4,300 22,200 80,000 2,800 2,600 65,400 71,000 35 141,300 73,400 153,900 368,600 14,800 7,500 146,300 142,000 1935-36 173,500 37,600 152,700 363,800 229,600 8,900 56,800 147,700 142,000 37 98,600 17,500 144,500 260,600 300,000 9,300 102,700 148,700 142,000 38 459,000 408,500 153,400 1,020,900 299,800 8,300 844,700 167,700 142,000 39 21,600 6,400 28,000 300,000 8,900 18,800 138,500 142,000 40 289,100 204,800 151,800 645,700 161,800 8,900 337,500 161,100 142,000 1940-41 466,300 543,700 150,600 1,160,600 300,000 7,400 974,900 178,300 142,000 42 322,300 389,000 148,300 859,600 300,000 7,800 698,100 153,700 142,000 43 169,100 175,600 157,800 502,500 300,000 8,500 343,100 150,900 142,000 44 68,700 7,900 82,200 158,800 300,000 10,000 65,300 141,500 142,000 45 96,700 11,700 123,200 231,600 242,000 9,100 38,700 148,900 142,000 1945-46 156,200 37,900 155,700 349,800 276,900 9,000 172,300 145,400 142,000 47 42,000 11,800 21,300 75,100 300,000 8,800 47,200 140,700 142,000 48 72,500 129,500 300 202,300 178,400 5,100 49,800 135,900 142,000 49 92,900 4,400 89,500 186,800 189,800 11,600 149,100 142,000 50 76,700 21,300 43,900 141,900 215,900 13,600 400 142,300 142,000 1950-51 208,800 129,100 141,800 479,700 201,500 12,800 230,500 137,900 142,000 52 317,900 309,800 147,100 774,800 300,000 12,800 626,500 135,600 142,000 53 224,300 174,800 143,500 542,600 300,000 12,800 388,700 141,100 142,000 54 147,500 67,900 150,100 365,500 300,000 12,000 216,400 137,100 142,000 55 56,400 36,400 32,600 125,400 300,000 9,700 70,200 141,800 142,000 1955-56 441,800 462,500 147,700 1,052,000 203,700 10,600 806,300 138,800 142,000 Average 160,500 115,500 95,500 371,500 238,600 9,200 216,900 143,500 140,400 * Includes the runoff from the tributary area between Clear Lake Dam and the Wilson Valley dam site and from North Fork Cache Creek. A-8 SEASONAL SUMMARY OP MONTHLY YIELD STUDY WILSON VALLEY RESERVOIR WITH 1,000,000 ACRE-FOOT STORAGE CAPACITY (In acre-feet) Seasonal yield: 252,000 acre-feet Flood control storage reservation of 65,000 acre-feet from November 1 to April 1 Season Inflow to Wilson Valley Reservoir Cache Creek: Spill from: Irrigation : below : Clear : release from: Total Clear Lake*: Lake : Clear Lake : Storage, October 1 Evaporation Spill Yield Release : at from : point of reservoir: diversion 1911-12 35,700 9,700 3,700 49,100 853,300 17,400 249,600 252,000 13 60,300 20,700 77,800 158,800 635,400 18,400 241,300 252,000 14' 423,600 465,700 151,600 1,040,900 534,400 23,600 429 ,300 257,000 252,000 15 334,300 411,900 145,600 891,800 865,300 21,700 560 ,200 276,700 252,000 1915-16 321,500 141,200 151,500 614,200 909,000 23,700 399 ,600 259,000 252,000 17 127,000 18,400 117,600 263,000 840,900 22,800 12 700 254,600 252,000 18 48,700 2,600 51,300 813,900 21,000 250,600 252,000 19 142,900 11,400 113,600 267,900 593,700 19,000 251,200 252,000 20 29,500 21,500 1,200 52,200 591,700 16, 100 252,600 252,000 1920-21 222,400 120,700 152,600 495,700 375,200 16,200 256,600 252,000 22 103,700 13,700 127,700 245,100 598,000 19,600 248,600 252,000 23 125,300 32,000 72,000 229,300 574,900 16,800 251,800 252,000 24 26,300 100 26,400 535,600 18, 100 250,800 252,000 25 154,100 96,200 122,600 372,900 293,100 9,400 244,200 252,000 1925-26 154,300 82,400 107,600 344,300 412,300 13,900 271,300 252,000 27 242,000 382,400 152,000 776,400 471,400 20,200 69 000 259,900 252,000 28 139,400 80,800 154,200 374,400 898,700 23,100 104 000 249,800 252,000 29 37,900 1,400 1,400 40,700 896,200 22,600 253,100 252,000 30 148,300 17,500 123,100 288,900 661,200 20,300 253,300 252,000 1930-31 16,600 1,500 18,100 676,500 16,600 244,100 252,000 32 87,500 3,800 91,300 433,900 13,300 248,800 252,000 33 43,000 3,900 46,900 263,100 8,500 252,300 252,000 34 53,500 4,300 22,200 79,900 49,200 3,800 118,600 126,000 35 141,300 73,400 153,900 368,600 6,700 5,500 257,200 252,000 1935-36 173,500 37,600 152,700 363,800 112,600 7,800 257,800 252,000 37 98,600 17,500 144,500 260,600 210,800 9,300 258,700 252,000 38 459,000 408,500 153,400 1,020,900 203,400 17,300 70; 900 277,700 252,000 39 21,600 6,400 28,000 858,400 19,800 248,500 252,000 no 289,100 204,800 151,800 645,700 613,500 20,2C0 86, 200 271,100 252,000 1940-41 466,300 543,700 150,600 1,160,600 881,700 17,900 831, 700 288,300 252,000 42 322,300 389,000 148,300 859,600 905,800 19,300 564, 700 263,700 252,000 43 169,100 175,600 157,800 502,500 917,600 21,300 280, 500 260,900 252,000 44 68,700 7,900 82,200 158,800 857,300 17,900 251,500 252,000 45 96,700 11,700 123,200 231,600 746,700 18,300 258,900 252,000 1945-46 156,200 37,900 155,700 349,800 701,100 18,700 255,500 252,000 47 42,000 11,800 21,300 75,100 776,600 18,800 251,600 252,000 48 72,500 129,500 300 202,300 581,300 12,000 242,400 252,000 49 92,900 4,400 89,500 186,800 529,000 20,400 259,100 252,000 50 76,700 21,300 43,900 141,900 436,300 20,100 252,300 252,000 1950-51 208,800 129,100 141,800 479,700 30s, 800 20,400 247,900 252,000 52 317,900 309,800 147,100 774,700 517,200 27,000 161, 000 244,800 252,000 53 224,300 174,800 143,500 542,700 859,100 28,200 262, 200 251,100 252,000 54 147,500 67,900 150,100 365,500 860,300 27,400 62, 800 242,800 252,000 55 56,400 36,400 32,600 125,400 892,800 22,800 251,800 252,000 1955-56 441,800 462,500 147,700 1,052,000 743,700 23,500 670, 100 248,800 252,000 Average 160,500 115,500 95,500 371,500 606,500 18,200 101, 400 252,000 249,200 * Includes the runoff from the tributary area between Clear Lake Dam and the Wilson Valley dam site and from North Fork Cache Creek. A-9 SEASONAL SUMMARY OF MONTHLY YIELD STUDY GUINDA RESERVOIR (In acre-feet) Storage capacity: Seasonal yield: 303,000 acre-feet 158,000 acre-feet Without flood control storage reservation : Yield Season Inflow to Gu inda Re servo 1 r Cache Creek:Spill from: Irrigation : below : Clear :release from: Clear Lake*: Lake : Clear Lake : Total Storage October 1 Evaporation Spill Release : at from : point of reservoir: diversion 1911 -12 56 900 9 700 3 ,700 70. 300 296 800 9 300 41, 500 162 300 158,000 13 97 800 20 700 77 800 196 300 154 000 10 400 153. 400 158,000 14 630 000 465,700 151 600 1,247 300 186 500 11 700 949, 500 175. 900 158, 000 15 499 400 411 900 145 600 1,056, 900 296, 700 10. 300 837, 400 209, 200 158,000 1915 -16 479 700 141 200 151 500 772. 400 296, 700 11 600 583, 700 176, 500 158, 000 17 194 000 18 '400 117 600 330. 000 297 300 11, 100 188, 100 170, 000 158,000 18 77 200 2 600 79, 800 258, 100 10 900 19, 400 163, 300 158, 000 19 217. 900 11 400 113 600 342. 900 144 300 11 100 55. 300 164 100 158,000 20 47 200 21 500 1 200 69. 900 257 000 10 400 5, 400 168; 700 158, 000 1920 -21 334 700 120 700 152 600 608, 000 142 400 10 200 266, 200 183. 700 158, 000 22 160 200 13 700 127 700 301, 600 290 400 11 900 145, 100 165, 900 158, 000 23 191, 900 32 000 72 000 295, 900 269. 200 9 300 169, 000 168 800 158, 000 24 42 400 loo 42. 500 218 000 12 300 161, 000 158, 000 25 234 100 96 200 122 600 452 900 87 200 7, 200 83, 200 167 200 158, 000 1925 -26 234, 000 82 400 107 600 424 000 282 500 9. 600 236, 500 208 200 158, 000 27 362 400 382 400 152 000 896 800 252 200 9 900 648, 000 198,800 158, 000 28 213, 600 80, 800 154 200 448, 600 292, 400 10, 900 261, 900 171, 800 158, 000 29 60, 400 1, 400 1 400 63, 200 296, 400 11, 000 41, 800 161, 200 158, 000 30 226, 500 17, 500 123 100 367, 100 145, 600 10, 300 66, 800 167, 000 158, 000 1930 -31 26, 800 1 500 28, 300 268, 600 9, 800 153, 400 158, 000 32 136, 000 3, 800 139, 800 133, 700 9, 600 159, 000 158, 000 33 68, 300 3, 900 72, 200 140, 900 7 600 164, 900 158,000 34 84, 600 4 300 22 200 111, 100 4, 600 5 600 76, 100 79, 000 35 211, 200 73, 400 153. 900 438, 500 34 100 8 800 182, 000 158, 000 1935 -36 264, 900 37, 600 152, 700 455, 200 281, 900 9, 500 252, 800 177, 100 158, 000 37 147, 400 17, 500 144 500 309, 400 297, 800 10, 900 134, 500 174. 800 158, 000 38 688, 600 408, 500 153, 400 1,250, 500 287, 000 8, 800 1,026, 100 204, 600 158, 000 39 34, 900 6, 400 41, 300 298, 000 9, 900 27, 900 156, 600 158, 000 4o 427, 300 204, 800 151, 800 783, 900 144, 900 9, 700 424, 200 197 200 158, 000 1940 -41 690, 900 543. 700 150 600 1,385, 200 297, 800 8 400 1,138, 900 239, 000 158, 000 42 473, 500 389, 000 148 300 1,010, 800 298, 100 9, 000 802, 200 200, 200 158, 000 43 259, 900 175, 600 157. 800 593, 300 297, 400 10 400 405, 300 177, 900 158, 000 44 170, 100 7, 900 82 200 260, 200 297, 000 9 100 92, 700 169, 000 158, 000 45 150, 600 11 700 123 200 285, 500 228, 400 10 000 69, 400 173. 600 158,000 1945 -46 244, 200 37, 900 155 700 437, 800 260, 900 9 700 222, 500 169. 000 158, 000 47 67, 300 11 600 21 300 100, 400 297 400 10 000 63, 000 162 500 158, 000 48 116 900 129 500 300 246, 700 162 300 6 900 47, 200 178 700 158, 000 49 145,700 4 400 89 500 239 600 176 000 13 700 4 800 172 600 158, 000 50 120, 400 21 300 43 900 185, 600 224, 400 15. 700 42, 300 167, 300 158, 000 1950 -51 319, 000 129 100 141 800 589, 900 184, 800 13, 700 301, 100 165, 300 158, 000 52 483, 100 309 800 147 100 940 000 294, 600 13, 600 762, 300 164, 100 158, 000 53 342 500 174 800 143 500 660, 800 294, 600 13, 300 475, 100 170, 700 158,000 54 227, 300 67 900 150 100 445, 300 296, 400 13 100 267, 000 175, 300 158, 000 55 89, 200 36,400 32 600 158, 200 286, 300 10 900 76, 600 169, 500 158, 000 1955 -56 655, 500 462 500 147 700 1,265, 700 187, 600 11. 500 981, 300 163, 700 158, 000 Average 244, 600 115 500 95 500 455, 600 221, 200 10, 400 271, 500 172, 500 156, 200 * Includes the runoff from the tributary area between Clear Lake Dam and the Guinda dam site and from North Fork Cache Creek. A-10 APPENDIX B COST ESTIMATES B-l TABLE OF CONTENTS Page Estimated Cost of Wilson Valley Dam and Reservoir With 300,000 Acre-Foot Storage Capacity . , . . B-3 Estimated Cost of Wilson Valley Dam and Reservoir With 1,000,000 Acre-Foot Storage Capacity „....„.... B-5 B-2 ESTIMATED COST OF WILSON VALLEY DAM AND RESERVOIR WITH 300,000 ACRE -FOOT STORAGE CAPACITY (Based on prices prevailing in June, 195?) Elevation of crest of dam: 1,129 feet, U.S.G.S. datum Elevation of crest of spillway: 1,108 feet Height of spillway crest, above stream bed: 24l feet Capacity of reservoir to crest of spillway: 300,000 acre -feet Capacity of spillway with 6 -foot freeboard: 63,000 second-feet Item Quantity • Unit price, in dollars Total cost, in dollars Dam Diversion and care of stream lump sum 500,000 Stripping and preparation of foundation 423,400 cu. yd. 1.75 71*1,000 Grouting Drilling 5,200 lin. . ft. 5.00 26,000 Pressure grout 7,800 cu. ft. 4.00 31 , 200 Embankment Pervious (new excavation) 1,612,200 cu. yd. 1.25 2,015,200 Pervious (salvage) 593,000 cu. yd. 0.20 118,600 Impervious 751,200 cu. yd. 0.80 601,000 Riprap 2,960 cu. yd. 6.ko 18,900 4,051,900 Spillway Excavation 625, 000. cu. yd. 2.25 1,406,200 Concrete Weir and lining 4,194 cu. yd. 50.00 209/700 Retaining walls 381 cu. yd. 80.00 30,500 Structural 880 cu. yd. 90.00 79,200 Reinforcing steel 1,023,900 lbs • 0.17 174,100 Drains 4,600 lin. ft. 5.00 23,000 Grouting lump sura 6,600 1,929,300 Outlet Works Tunnel 1,250 lin, , ft. 1,260.00 1,575,000 Excavation Inlet portal 66, 10C cu. yd. lo75 115/700 Outlet portal and stilling basin 52,700 cu. yd. 1-75 92,200 Concrete Inlet structure Lining 150 cu. yd. 80.00 12,000 Structural 22 cu. yd. 90.00 2,000 Outlet structure Foundation 29 cu. yd. 50.00 1,400 Structural 95 cu. yd. 90.00 8,600 Stilling basin Lining 220 cu. yd. 50.00 11,000 Retaining walls 133 cu. yd. 80.00 10,600 Structural 27 cu. yd. 90.00 2,400 Gate chamber plug Semi -structural 850 cu. B-3 yd. 80.00 68,000 ESTIMATED COST OF WITH 300,000 ACRE- WILSON VALLEY DAM AND RESERVOIR ■FOOT STORAGE CAPACITY (continued) Item I Quantity :Unit price, : : in dollars : Total cost, in dollars Outlet Works (continued) Reinforcing steel 113,000 lbs. 0.17 19,200 Steel pipe 2 each, 60" dia., l/4" plate, 840' long 286,000 lbs. 0.30 85,800 Pipe supports lump sura 10,300 Miscellaneous metal (trashrack, stop logs, etc .) 300,000 lbs. 0.30 90,000 High-pressure gate valves, 4' x 4' 2 each 34,000 68,000 Howell-Bunger valves, 54" diameter 2 each 54,000 108,000 Riprap 150 cu. yd. 6.40 1,000 Air vent, 12" diameter 210 lin, ft. 50.00 10,500 2,291,700 Reservoir Land and improvements State highway relocation Clearing Subtotal Engineering and adminis- tration, 10 per cent Contingencies, 15 per cent Interest during construction, 4 per cent for l/2 of 2 -year period TOTAL CAPITAL COST 4,000 acres lump sum 273,800 lump sum 4,610,000 100.00 400,000 5,283,800 13,556,700 1,355,700 2,033,500 677,800 17,623,700 ANNUAL COST Interest Repayment Replacement Operation and maintenance General expense TOTAL ANNUAL COST 704,900 115,400 12,300 24,500 56,400 913,500 B~4 ESTIMATED COST OF WILSON VALLEY DAM AND RESERVOIR WITH 1,000,000 ACRE -FOOT STORAGE CAPACITY (Based on prices prevailing in June, 1957) Elevation of crest of dams 1,244 feet, U.S.G.S. datum Elevation of crest of spillway: 1,228 feet Height of spillway crest, above stream bed; 3ol feet Item Capacity of reservoir to crest of spillway: 1,000,000 acre -feet Capacity of spillway with 6 -foot freeboard: 4-5,000 second-feet Quantity :Unit price, : ; in dollars : Total cost, in dollars Dam Diversion and care of stream Stripping and preparation of foundation Grouting 886,050 cu. yd, lump sum 600,000 1=75 1,550,600 Drilling 11,400 lin, ft. 5.00 57,000 Pressure grout 17A00 cu. ft. 4.00 68,400 Embankment Pervious (new excavation) 5,193,000 cu. yd. 1.25 6,491,200 Pervious ( salvage ) lj ,468,400 cu. yd. 0.20 293,700 Impervious 1. ,93^,710 cu. yd. 0.80 1,547,800 Riprap 4,220 cu. yd. 6.40 27,000 10,635,700 Spillway Excavation 1 ,378,000 cu . yd . 2.25 3,100,500 Concrete Weir and lining 5,647 cu . yd . 50.00 282,400 Retaining walls 1,322 cu. yd. 80.00 105,800 Structural 91.0 cu. yd. 90.00 81,900 Reinforcing steel 1, ,126,100 lbs. 0.17 191,400 Drains 6,500 lin. ft . 5.00 32,500 Grouting lump sum 10,600 Radial gate, 40" x 30" 1 each lump sum 49,500 Radial gate hoist 1 each lump sum 21,300 3,875,900 Outlet Works Tunnel 1,679 lin. ft. 1,260.00 2,115,500 Excavation Inlet portal 80,700 cu. yd. 1.75 141,200 Outlet portal and stilling basin 55,000 cu. yd. 1.75 96,200 Concrete Inlet structure Lining 180 cu. yd. 80.00 14,400 Structural 120 cu. yd. 90.00 10,800 Outlet structure Foundation 33 cu. yd. 50.00 1,700 Structural 120 cu. yd. 90.00 10,800 Stilling basin Lining 360 cu. yd. 50.00 18,000 Retaining walls 184 cu. yd. 80.00 14,700 Structural 61 cu. yd. 90.00 5,500 B-5 ESTIMATED COST OF WILSON VALLEY DAM AND RESERVOIR WITH 1,000,000 ACRE -FOOT STORAGE CAPACITY (continued) Item Quantity :Unit price, : Total cost, : in dollars : in dollars Outlet Works (continued) Concrete (continued) Gate chamber plug Semi -structural 830 cu. yd. 80.00 66,400 Reinforcing steel 187,200 lbs. 0.17 31,800 Steel pipe 2 each, 72" dia., 7/16" plate, 1,280* long 915,000 lbs. 0.30 274,500 Pipe supports lump sum 32,900 Miscellaneous metal (trashrack, stop logs, etc ) 500,000 lbs. 0.30 150,000 High-pressure gate valves, 4-1/2* x 4-1/2' 2 each 61,600 123,200 Howell -Bunger valves, 66" diameter 2 each 72,000 144,000 Riprap 350 cu. yd. 6.4o 2,200 Air vent, 12" diameter 424 lin. ft. 50.00 21,200 3,275,000 Reservoir Land and improvements Clearing State highway relocation Subtotal Engineering and adminis- tration, 10 per cent Contingencies, 15 per cent Interest during construction, 4 per cent for 1/2 of 3-year period TOTAL CAPITAL COST 9,000 acres lump sum 546,700 100.00 900,000 lump sum 4,610,000 6,056,700 23,843,300 2,384,300 3,576,500 1,788,200 31,592,300 ANNUAL COST Interest Repayment Replacement Operation and maintenance General expense TOTAL ANNUAL COST 1,263,700 206,900 22,100 67,000 101,100 1,660,800 B-6 APPENDIX C GEOLOGY OF WILSON VALLEY AND GUINDA DAM SITES ON CACHE CREEK C-l TABLE OF CONTENTS Page CHAPTER I. INTRODUCTION. .................. C-5 Prior Investigations and Reports . . . . . . . . , . . , . . . c-6 Exploration Program. . .......... . . . . . . . . . . C-7 Wilson Valley Dam Sites ................. C-7 Guinda Dam Site ..................... C-9 Conclusions ......................... C-10 Wilson Valley Dam Sites ................. c-10 Guinda Dam Site ................. . . . . c-11 CHAPTER II. GEOLOGY OF WILSON VALLEY DAM SITES ....... C-13 vjrt2 II" x ci _L vjt" \j J-\J Qy o © o o * o « o • o ft o c o © o « c o o o o 0""J-j3 Geology of Upper Dam Site. .................. C-l6 Left Abutment ...................... C-16 Right Abutment. ..................... C-I7 Cnannex oeccion ..................... C— 17 Stripping Estimates ................... C-18 i\C OCI VUII o c o o * e « e • o © © © • • • * © o o « o O ~" J- ^7 Geology of Lower Dam Site. .................. C-20 Left Abutment .............. . C-20 Right Abutment. ............. ... C-20 Channel Section ..................... c-21 Stripping Estimates ................... C-21 OJJJ-J-J-Wci^yo O O O © O O © O O © 9 • © © © • \J ~~ CL CL UCuCl v U J.1 o © • © © © o • © © © o © © © * • e c c L/"~£_ s 3 C~2 TABLE OF CONTENTS (continued) Page 0"J.OIflXOJ.L' t y o o o • o o e » o • © a o c o • o o • c e a o « • • C — 2 ") Suitability of Sites ..................... C-24 Construction Materials . . „ . . . . . . c . . . . . . . , C-25 *"^ooo • • • ° * • ° • ° ° • • • • ° * • • • ■ ° • ° ° O — ^ O X^"XVX^JUOi/XJ-J- # o o o o o « v o o o o © • © © o © © Q-^h Impervious or Random Fill . . . . . . . . o . * . . « . . C-27 XlJ-^/X G^/ *oooooooooo0ooeooeeot>oe«ee K^f mm C f OUIIUllclX \/ o o o o o o o © o q o c o * o o o o o « ■ o o c e o o O ~ C ( CHAPTER III. GEOLOGY OF GUINDA DAM SITE. C-29 Geology of Dam Site. . ................... . C-31 J_J0 XL/ nUUU mG ilTy o c o « « o © e a o o e o © o © * © © v — ,3 £- Ill^n w ADUTym0nT^ oooooooooooooog©©**©*© ^""jJO OiJciriric-L u6c Dion »*•««••••••«••••••••« ^- / ""^j5 Stripping Estimates . . . C-36 Opi J. -LWay . oo.ooceoeo.oo.oc.o.oooeo U — Jj f rieservoir ..«.««..••»»*»..•*•«.«•* — _)o oeismiciuy .......................... l> _ jy Suitability of Site. ••••••••••••.••. C-40 Construction Materials ........ .... C-4l ooiJL iesi/S* .. ......... ............ u~m-j_ OU mma ry «oeoeoooo»o.oo©«o.oeeoooooooL< — <— C-3 PLATES Plates CI through C6 are bound at end of this appendix. Plate No. CI Areal Geology of Upper and Lower Wilson "Valley Dam Sites C2 Geologic Sections of Upper and Lower Wilson Valley Dam Sites C3 Possible Sources of Construction Materials., Wilson Valley Dam Site C4 Isoseismal Map for Earthquake of May 7 » 1955 C5 Geology of Reservoir Area and Location of Soil Samples., Guinda Dam Site C6 Surface and Subsurface Geology and Location of Test Holes ., Guinda Dam Site C-4 CHAPTER I. c INTRODUCTION Preliminary geologic explorations have been conducted by the Department of Water Resources for the purpose of investigating two alternative reservoir sites on Cache Creek. Two separate exploration programs were undertaken -- an investigation of Guinda dam site located in the vicinity of Guinda,, Yolo County, and an in- vestigation of two Wilson Valley dam sites located downstream from the confluence of Cache Creek and North Fork Cache Creek . During the spring of 1953^ preliminary geologic explora- tion was undertaken in the vicinity of the town of Guinda , Yolo County, for the purpose of locating a suitable site for the construc- tion of an earthfill dam. A dam at this site would control the run- off from approximately 992 square miles of drainage area. During the early winter of 1955 and the spring and early winter of 1956, a program of geologic exploration was conducted in the Wilson Valley area on Cache Greek. The purpose of this explora- tion was to determine the most favorable location for construction of an earthfill dam. A dam at the Wilson Valley site would control the runoff from an area of approximately 793 square miles. The location of the dam sites is shown on the locality map on Plate CI, "Areal Geology of Upper and Lower Wilson Valley Dam Sites". General structural features of the Wilson Valley area covered by this report include large complex folds and steeply dip- ping faults, some of which are several miles in length. These fea- tures trend northwestwardly. The Guinda dam site is located in an area of younger and less deformed rocks. Capay Valley is a broad., elongated, synclinal C-5 valley bounded on the east by an asymmetric anticline and on the west by an easterly dipping homoclinal structure . Minor folds and two faults , one of which is a thrust fault, are also present. Geologic formations through which Cache Creek flows are primarily sedimentary and range in age from Recent to Upper Jurassic. These include the Tehama and Cache formations of Plio-Pleistocene age, the Capay formation of Eocene age, the Chico formation of Creta- ceous age, and the Knoxville group of Upper Jurassic age. The area investigated is in the geomorphic stage of early maturity. The general topography near the Wilson Valley sites consists of irreg- ular hilly areas with a complex stream pattern, while the Guinda site is located in a broad flat valley surrounded by low hills. Prior Investigations and Re ports The following reports were utilized during the preparation of this reports 1. Anderson, C. A, and Russell, R. D., "Tertiary Formations of Northern Sacramento Valley, California". California State Department of Natural Resources, Division of Mines, Journal of Mines and Geology. Volume 35. 1939. 2. Borglin, Edgar K., "The Geology of a Part of the Morgan Valley Quadrangle", University of California, Master's Thesis. 19^9. 3. Brice, James C, "Geology of Lower Lake Quadrangle, California". California State Department of Natural Resources, Division of Mines. Bulletin No. 166. April, 1953. 4. Crook, T. H. and Kirby, J. M. , "Capay Formation". Geological Society of America Proceedings, 193^-1935. 5. Kirby, J. M. , "Upper Cretaceous Stratigraphy of West Side of Sacramento Valley South of Willows, Glenn County, California". Bulletin American Association of Petroleum Geologists. Vol- ume 27. No. 3. 19^3. 6. Kirby, J M. , "Rumsey Hills Area". California State Depart- ment of Natural Resources, Division of Mines. Bulletin No. 118. March, 19^3. C-6 7. Lawton, John E. "Geology of the North Half of Morgan Valley and South Half of Wilbur Springs Quadrangle", Stanford University, Doctor of Philosophy Thesis. 195^. (Geologic map and cross sections only utilized in this report, ) 8. Northern California Geological Society , Pacific Section American Association of Petroleum Geologists. "Spring Field Trip, May 7~8.-»195 i +j Capay Valley to Wilbur Springs, West Side Sacramento Valley, California". May 7, 1954. 9. U. S. Department of Commerce - U S„ Coast and Geodetic Survey., "Abstracts of Earthquake Reports for the Pacific Coast and Western Mountain Region"., (annual and biannual compilations) (1940 to present ) 10. Wood, H. 0. and Heck, N. H "Earthquake History of the United States, Part II - Stronger Earthquakes of California and West- ern Nevada". United States Department of Commerce., Coast and Geodetic Society. (1769 through 19^0 ). Exploration Program Limited programs of geologic exploration were conducted at the Guinda and Wilson Valley dam sites. In general, the programs comprised surface geologic mapping, subsurface explorations along the axes of the dam sites and in the spillway areas, and collection of soil samples for laboratory testing. Particular attention was given to the condition of the rock, including degree of weathering, pat- terns of jointing, and the nature and extent of shear zones. Wilson Valley Dam Sites Two axes, designated the upper and the lower, were explored by the Department of Water Resources in 1955 and 1956, The upper site is located at a narrow constriction in the canyon of Cache Creek immediately below Wilson Valley. The lower site is located about 1 mile farther downstream and is immediately below a right angle bend where the stream channel changes from a southeast to a southwest direction. Dam site locations are shown on Plate CI. C-7 The exploration program consisted of the following; sur- face geologic mapping of the upper and lower sites, exploratory drilling along the dam axis and spillway area at the upper site, exploratory drilling near the dam axis at the lower site, dozing cuts and trenches in the spillway area at the lower site, and collec- ting soil samples from potential borrow areas for laboratory tests. Three test holes were drilled along the dam axis of the upper site. Total footage in the three holes amounted to 309.7 feet. Two of these holes were located in the channel and were drilled at angles so as to intersect at about 60 feet beneath mid-channel. These holes were used to determine the depth of channel sands and gravels, the presence of any faults, and the character of the founda- tion rock below the channel. The third hole was drilled through landslide and colluvial material into relatively fresh Knoxville sediments in order to determine the depth of stripping. Four test holes, numbered WV1L, WV2L, WV3L, and WV4L, were drilled into the left abutment area and along the proposed dam axis at the upper site c The total footage of these holes amounted to 282.0 feet. These holes were located to determine the thickness and character of the Cache formation. At the lower site six test holes were drilled. Two of these were located in the channel to detect the presence of any faults, to determine the character and thickness of the stream depos- its, and to determine the character of the foundation rock. One hole was drilled in the left abutment to determine the character of the upper portion of the abutment. This information was required primarily to ascertain stripping estimates c On the right abutment three holes were drilled through the fractured and broken rock of C-8 the abutment into relatively fresh material. Five exploratory trenches and angle cuts were made by a D-8 tractor and bulldozer in the upstream approach and ridge crest of the spillway area. These cuts and trenches were examined to determine the lithologic character of the material, to detect the presence of any faults in the spillway area., to determine resistance to stripping., and to ascertain the stability of various slopes. Detailed logs are in the files of the Department of Water Resources. Cores obtained from the drilling pro- gram are also available for inspection. Location of test holes, exploratory drifts, and bulldozer cuts; the location of cross sections along the axes; and detailed distribution of geologic formations present in the dam site areas are shown on Plate CI. Geologic cross sections A-A 3 and B-B 1 are shown on Plate C2, entitled "Geologic Sections of Upper and Lower Wilson Valley Dam Sites,, Cache Creek". Guinda Dam Site The exploration program included surface geologic mapping in Capay Valley from Guinda to the north end of the valley, a seismic survey along the selected dam site axis, exploratory drilling along the axis of the dam and in the abutments and spillway area., and collection of soil samples for laboratory tests. Six rotary test holes were drilled across the valley along the axis of the proposed dam. Total footage in the six holes amounted to ?4o feet. Approximately 52.5 feet of coring was attempt- ed in the underlying slightly to moderately compacted Tehama forma- tion of Plio-Pleistocene age., with a core recovery of about 88 per cent. In addition to the six deep test holes, nineteen shallow C-9 power auger holes were drilled in the abutments to determine depths of overburden and physical characteristics of sediments., and twelve shallow hand auger holes were drilled in the valley fill to obtain soil samples for laboratory tests. Seven additional soil samples from test pits and two samples of the stream channel gravels were obtained for various soil tests. Detailed results of soil tests and a seismic survey are in the files of the Department of Water Resources c Cores of the Tehama, formation from the six test holes are available for inspection. The surface distribution of the geologic formations in the reservoir area is shown on Plate C5* entitled "Geology of Reservoir Area and Location of Soil Samples, Guinda Dam Site". Detailed dis- tribution of geologic formations and subsurface sequence of strat- igraphic units and structural conditions of the dam site are shown on Plate C6, "Surface and Subsurface Geology and Location of Test Holes,, Guinda Dam Site". Conclusions As a result of the geologic surveys and studies during the current and prior investigations, the following conclusions have been reached. Wilson Valley Dam Sites 1. The presence and depth of Cache formation sediments at the spillway , the gouge zone in the channel, and the thickness of the colluvial material on the right abutment make the upper site less desirable than the lower site. 2. Geologically, the lower site is best adapted to an C~10 earthfill type dam with a spillway either through the saddle north- east of the left abutment or along the left abutment. Guinda Dam Site 1. Preliminary geologic studies have not indicated the presence of any serious defects that might preclude the construction of an earthfill dam at this site. 2. The site is best adapted to an earthfill type dam with a spillway through an existing saddle behind the left abutment. C-ll CHAPTER II. GEOLOGY OF WILSON VALLEY DAM SITES The following discussion of the geologic characteristics of the Wilson Valley dam sites, based on the findings of prior re- ports and field investigation by Department geologists, includes surface geologic mapping, underground exploration, and material sampling and testing. General Geology The geologic formations in the Wilson Valley area consist of sedimentary and ultra-basic rocks of Upper Jurassic age, unconsoli- dated lacustrine and fluviatile deposits of Plio-Pleistocene age, and Recent terrace and alluvial deposits. The Knoxvllle group of Upper Jurassic age is the oldest lithologic unit encountered In this area. The sediments found con- sist primarily of gray to black marine shale and siltstone inter- bedded with smaller amounts of graywacke-type sandstone, deposits of chert and limestone varying from thin beds to lenticular bodies, and locally prominent conglomerate zones. The sedimentary beds trend generally N40 W to N70 W and dip 40 to 80 northeast; although some beds are vertical. The predominant strike in the spillway area of the lower site is N20°W. Ultra-basic rocks, predominantly altered to serpentine, occur in large bodies throughout the Jurassic formations of the Coast Range, but no outcrops of this material are evident aloni Cache Creek in the vicinity of the dam sites. A large body of ser- pentine, trending northwestwardly, was mapped 0.5 mile east of the proposed dam sites. The Cache formation, of Plio-Pleistocene age, is a thick deposit of poorly consolidated gravel and silt that was laid down in C-13 rivers and fresh water lakes. The major portion of this formation terminates at the upper end of Wilson Valley . However,, an outcrop approximately 3*000 feet long was mapped in the proposed spillway area of the upper site. The maximum thickness of the Cache formation, as determined in the report on "Geology of Lower Lake Quadrangle", exceeds 1 mile. Cache beds in the above-noted outcrop area exceed 177 feet in thickness, as indicated by hole WV1L, and probably are not more than 400 feet thick locally. This maximum thickness in the dam site vicinity was determined from the cross section B-B 1 , as shown on Plate C2„ Recent terrace deposits cover the major portion of Wilson Valley except in the present channel area of Cache Creek. The ter- race deposits consist of well-compacted, light-brown to tan silts underlain by coarser gray-brown sandy and gravelly silts. Gravel beds and sand lenses were also found. The depth of terrace beds and lenses exceeds 20 feet as determined by auger holes drilled in the proposed borrow areas of the valley. Several terrace deposits were found at elevations higher than Wilson Valley indicating Pleistocene or younger uplift and rejuvenation in that age. Within the channel are found Recent alluvial and stream channel deposits. These deposits are composed primarily of highly pervious loose sand and gravel. Red sandy clay forms a matrix for a few of these deposits. Although the U. S. Corps of Engineers mapped extensive areas adjacent to Cache Creek as Quaternary landslide debris, i.e., slides of all rock types, recent exploration of the Department of Water Resources has indicated this material is the mantle of soil and broken rock identical to the fresher material found beneath. A C-14 better term than landslide debris would be colluvial material, and this terminology is employed in this report . True landslides and talus deposits, although not extensive in the dam site area, are exceedingly common. The majority of these occur on a dip slope where the present stream parallels the strike of the underlying Knoxville group. The general structural features of this region of the Coast Range are large complex folds with northwestwardly trending axes which are several miles in length and moderately narrow in width. Throughout the region steeply dipping faults also trend in a north- westward direction. Some have a length of many miles with displace- ments measurable in hundreds of feet. Deformation is much less pronounced in the Plio-Pleistocene Cache formation than in the underlying older sediments. Dips in the Cache formation rarely exceed 30° and commonly are nearly horizontal. Faulting in this region is indicated by zones of crushed and slickensided sediments and abnormally straight contacts between formations. Minor faults are indicated by the observed displacement of strata. The majority of faults mapped were discernible only be- cause they are, in part, contacts between major rock units. Other large faults are probably present within the major rock units as dis- cussed in the James C. Brice report but are not discernible because of the uniformity of the unit and soil cover. The general topography of this region consists of irregular hilly areas, the drainage of which is generally adjusted to the north- west structural trend. However., the stream pattern is complex with many insequent gullies dissecting the topography. Most of the regions C-15 in the stream valleys are now in the geomorphic stage of early ma- turity. Several irregular flat-bottomed valleys,, such as Wilson Valley, are seen throughout the area. Geology of Upper Dam Site Foundation rock at the proposed upper site consists of steeply dipping consolidated Knoxville shales, siltstones, and sand- stones overlain by the poorly consolidated Cache formation. Terrace gravels outcrop on the left abutment. Silts, sands, and gravels occur within the stream channel in deposits of considerable thick- ness . Left Abutment The lower portion of the left abutment consists of badly fractured beds of Knoxville shales and siltstones. The strike of O n these beds generally intersects the stream channel at 10 to 30 . Overlying the Knoxville group is an outcrop of relatively pervious terrace gravels which forms a gently sloping nose. The thickness of these terrace gravels, as determined from the U. S. Corps of Engineers drill holes 7F-1, is 8 feet. Farther down the slope this deposit probably increases in thickness. Core obtained from the 7F-1 drill hole also indicated that the Knoxville formation consists of fine, dense, fractured brown clay shales. The prominent dip of the forma- tion is 50°. Beds of the poorly consolidated and moderately pervious Cache formation overlie the Knoxville group and extend northeastwardly from near drill hole WV2L to beyond the spillway location. Drill hole WV1L indicates that the Cache formation is at least 177 feet thick. This pervious part of the left abutment would require C-16 impervious blanketing throughout its extent below the water surface. No indication of faults through this abutment was evident . A moderate grout take would be required to produce a satisfactory foundation. Right Abutment The Knoxville group forms the foundation rock of the en- tire right abutment as shown on Plates CI and C2. The beds on this side of the creek strike more nearly east-west than on the left abut- ment,, thus giving the indication of a possible fault in the channel „ General lithology is the same as the Knoxville group of the left abutment . Drill hole RA-1 indicates that this abutment would have to be stripped a minimum of 35 feet. Logs of the U. S. Corps of Engineers drift 4F-1 show west dipping fractured shales and silt- stones overlain by 15 feet of overburden. These logs indicate a water seep at the extreme end of the drift. Grout take would prob- ably be moderate. Channel Section Recent alluvial and stream channel deposits cover the channel section to a depth of approximately 15 feet. These deposits are composed of silts, sands.? and gravels. The gravels vary in size from granules to boulders. These are lying on the Knoxville group through which Cache Creek has cut its present channel. The Kennedy fault, recently mapped by Lawton and discussed in his report, is found intersecting the axis at mid-channel. This near vertical fault zone, with a minimum width of 45 feet, consists of gouge ma- terial as indicated by drill hole LC-1. Several shear zones and one C-17 gouge zone approximately 10 feet wide in horizontal projection were seen in drill hole RC-1., which penetrated only a short distance into the fault zone. The Kennedy fault zone has a great bearing on the feasibility of this upper dam site. This will be indicated in the section on stripping estimates. Grout take for the channel section in general would probably be moderate. Stripping Estimates The following stripping estimates given are for the pro- posed earthfill dam. Depths of stripping are estimated normal to the ground surface. On the left abutment an average of 5 feet would have to be stripped from the entire slope. The area beneath the impervious section would require an additional stripping of 15 feet. This should remove the weathered and fractured zone and should expose suitable foundation materials. On the right abutment an average of 40 feet would have to be stripped from the entire slope. This should remove the weathered zone and colluvial material and expose suitable foundation material. The channel width between abutments is approximately 130 feet, and the channel section is filled with Recent alluvial de- posits averaging 15 feet in depth. Beneath these deposits there are about 10 feet of weathered bedrock and a zone of about 45 feet of badly broken bedrock and gouge material. These unsuitable mate- rials must be removed before placing the impervious fill. The above stripping should expose a suitable foundation for the impervious section of the proposed dam. Only the excavation necessary for shaping the foundation will be required beneath the pervious fill. C-18 Spillway The proposed spillway would be located through the saddle north of the left abutment. Due to the depth of the poorly consoli- dated, moderately pervious Cache formation , the spillway would require impervious blanketing of this zone below the water surface. If it could be determined that an impervious zone or bed exists, such ex- tensive blanketing would not be necessary. Due to the presence of Cache formation beds over 150 feet thick at the upper site, the construction of the spillway there would require careful engineering consideration regarding blanketing. Downstream protection of the spillway area and the earthen dam would also have special engineering requirements because of erosion prob- lems. In any event, lining of the entire spillway would be necessary. The Wilson fault, if present, would not create any problem due to its distance from the spillway location. Reservoir Leakage from the upper reservoir through the Knoxville formation would be slight. However, leakage from the reservoir of the upper dam through the relatively pervious Cache formation on the left abutment could possibly be great unless suitable precautions are taken. Several cattle ranches lie within the proposed reservoir. Few crops are grown j however, some apiaries are found in the reser- voir area. A section of State Highway 20 which crosses the proposed reservoir, the bridge across North Fork Cache Creek, and the Cache Creek school would have to be relocated if a dam is built at this axis C-19 Geology of Lower Dam Site Except for the stream channel deposits the foundation rock at the lower site consists entirely of lithologic units of the Knox- ville group. The Knoxville units include, in decreasing order of abundance, silty sandstones, siltstones or mudstones, and silty shales. Calcite veining is present locally. The Recent channel deposits con- sist of highly pervious sand and gravel. The Knoxville beds strike across the channel and dip rather steeply upstream. Left Abutment The entire abutment consists of alternating beds of Knox- ville sandstones and siltstones with minor mudstones and shales . as shown on Plates CI and C2. The one left abutment drill hole (LA-l) indicated that this abutment is highly fractured and weathered to 20 feet below the ground surface. Below that depth, water loss was 100 per cent throughout the 103 .0 feet of hole. This indicated that the rock is badly fractured to that depth. However, this hole pene- trated only 40 feet into the abutment, on a line perpendicular to the surface. This abutment has a very steep face near the stream channel; consequently, only minor slides of weathered surface material are evident. Hole 1F-4 of the U. S. Corps of Engineers indicates a weath- ered zone 10 feet thick which consists of shale and sandstone fragments. The remaining 152 feet of this hole consists of sandstones and silty shales, locally veined with calcite. Due to the fractured nature of the material the grout take would probably be moderate. Right Abutment This abutment is also composed entirely of lithologic units of the Knoxville group. As on the left abutment, sandstone ribs C-20 appear to be predominant over the more easily weathered siltstone. The steeply dipping character of the beds and the fact that the beds strike across the channel have limited the formation of slide mate- rial, especially on the lower slope of this abutment. The three drill holes located on this abutment indicate that soil cover is about 2 feet deep and that the zone of highly fractured and weathered sandstones and siltstones varies from 10 to 20 feet deep. Grout take would be moderate, but less than at the upper site. Channel Section Recent alluvial and stream channel deposits cover the chan- nel section to a maximum depth of 12 feet. Below the stream channel deposits the Knoxville formations are broken, fractured, and iron- stained to a depth of about 30 feet. Drill holes RC-1 and LC-1 showed that the siltstones, sandstones, and shales found in the channel are suitable for the proposed earthfill dam. Grout take would be moderate due to the fractured nature of the foundation rock. No evidence of a fault could be inferred from either of the two channel holes . Stripping Estimates The following stripping estimates are for the proposed earth- fill dam. Depths of stripping are estimated normal to the ground surface. On the left abutment approximately 10 feet of loose bedrock and soil would have to be stripped from the slope. The area beneath the impervious section would require additional stripping of 30 feet to expose suitable foundation material. C-21 On the right abutment approximately 5 feet of soil should be removed from the entire abutment area. An additional 20 feet of weathered and broken bedrock would have to be stripped from the imper- vious core area. The channel width between abutments is approximately 150 feet. The channel section is filled with an average thickness of 15 feet of stream channel deposits underlain by about 15 feet of weathered bedrock. All of this material must be removed from beneath the impervious section. However , only the excavation necessary for shaping the foundation will be required beneath the pervious fill. Spillway The proposed spillway for this site may be located either through the saddle northeast of the left abutment or along the left abutment. The entire spillway area is underlain by mudstones, silt- stones, and sandstones of the Knoxville group. Although no drill holes were included in the recent exploration program, extensive trench- ing was completed during November, 1956. The trenching program included five exploratory trenches and three angle cuts as shown on Plate CI. The trenches were excavated to determine the character of the spillway materials in regard to both foundation and earthfill characteristics. The angle cuts, one 30 , one 45 , and one 60 , measured from a horizontal plane, were designed to test the stability of slopes in Knoxville mudstones and sandstones. Inspection at a later date will give an indication of the stability of the spillway cuts. The average strike and dip of the beds inter- sected by the trenches was N20°W and 44°NE, respectively. The depth and amount of excavation for this spillway, as in- dicated by Plate C2, would be considerable. The spillway cuts should C-22 be stable at slopes of approximately 1:1. Due to the extreme depth of cut, benches at regular intervals might prove essential. Removal, of the material would be classified as common excavation. Lining of the entire spillway and probably some type of cutoff would be necessary to prevent erosion of the Knoxville sediments. Reservoir Leakage from the reservoir through the Knoxville formation would be slight. Several cattle ranches lie within the proposed reservoir. Few field crops are grown; however, some apiaries are found in the reservoir area. A section of State Highway 20 which crosses the pro- posed reservoir, the bridge across North Pork Cache Creek, and the Cache Creek school would have to be relocated if a dam is built at this axis. Seismicity The proposed Wilson Valley dam sites are not located in an area of strong seismic activity. However, several shocks have occurred in the past which would probably have caused damage to an earth dam or such related structures as canals and tunnels. These shocks were lo- cated in the vicinity of Clear Lake. Intensities of earthquakes discussed below correspond to the Rossi-Forel Scale of Earthquake Intensity, This scale ranges from I to X in intensity. It is based on reports of persons feeling the shocks and on the damage incurred. Three shocks of intensity VI were recorded on April 29, 1955, with the epicenter near the town of Kelseyville, These were sharp C-23 shocks felt over an area of approximately 900 square miles in the vicinity of Clear Lake. The over-all damage was slight. An inten- sity of IV was reported from Lakeport, Morgan Valley, and Siegler Springs. Three shocks were again recorded on May 7, 1955. The in- tensity was recorded as VI with the epicenter again near the town of Kelseyville. The second and principal shock was felt over an area of approximately 2,000 square miles, primarily in Lake County. Mod- erate damage occurred to buildings, and some ground cracks appeared at Clearlake Park. The location of the above epicenters is approximately 20 airline miles from the dam sites. Although no epicenters have been recorded In the immediate vicinity of the dam site, it is reasonable to assume that this area could be subjected to earthquakes of con- siderable intensity. The location of the epicenter and the delineation of shock zones is shown on Plate C4, "Isoseismal Map for Earthquake of May 7 , 1955" . Suitability of Sites Both the upper and lower sites appear to be best suited for earthfill type dams. The upper site is unsuitable for a concrete- gravity type dam. Further exploration at the lower site might justify consideration of that axis for a low concrete-gravity type dam. Preliminary tests indicate that the rocks of the Knoxville group would provide a satisfactory foundation for the earthfill dam under consideration. As indicated in the introduction, one purpose of this report- was to determine the relative feasibility of the two proposed dam C-24 sites. From the included data it is evident that the lower site is more suitable for an earthfill dam than the upper site. The primary disadvantages of the upper site are the presence and depth of Cache formation sediments at the spillway,, the gouge zone in the channel, and the thickness of the colluvial material, on the right abutment . Construction Materials Aggregate Channel deposits extending 1.3 miles downstream from the State Highway 20 bridge across the North Fork Cache Creek were sampled and found to be suitable for use as concrete aggregate. The average haul distance for this group of deposits is approximately 6 miles from the lower axis measured along the stream channel,, Based on an average depth of 3 yards, the volume of the aggregate materials is conserv- atively estimated to be 500,000 cubic yards. Location of the aggre- gate material is shown on Plate C3> "Possible Sources of Construc- tion Materials, Wilson Valley Dam", Pervious Fill A group of channel deposits considered best suited for use as pervious fill extends along Cache Creek from the south end of Wilson Valley to the lower dam site. The average haul distance for this group of deposits is approximately 1 mile from the lower axis measured along the stream channel. Samples were taken near the lower dam site axis. The results of laboratory tests made on these samples showed them to be better suited for use as pervious fill than aggre- gate because of grading deficiencies . However, such material, with proper processing, may be used for aggregate. No special processing C-25 is contemplated for their use as pervious fill. Based on an average depth of 3 yards., the volume of this group of channel deposits is conservatively estimated to be 364,000 cubic yards . For the location of pervious material see Plate C3« The channel deposits extending upstream approximately 2 miles from the State Highway 20 bridge over North Pork Cache Creek have not been sampled, but are probably suitable for use as pervious fill. The average haul distance for this group of deposits is approx- imately 9 miles from the lower axis, measured along the stream channel. Based on an average depth of 3 yards, the volume of the above-mentioned deposits is conservatively estimated to be 2,173*000 cubic yards. The area is not designated on Plate C3« A third group of channel deposits extends from approximately 1 mile below the State Highway 20 bridge over North Fork Cache Creek to the confluence of Cache Creek with Rocky Creek. These deposits have been examined only visually in the field. They are probably suitable for use as pervious fill. The average haul distance for this group of deposits is approximately 5 miles from the lower axis, meas- ured along the stream channel. Based on an average depth of 3 yards, the volume of the deposits is conservatively estimated to be 1,213*000 cubic yards. For location of these deposits see Plate C3. A fourth group of channel deposits extends approximately 4 miles downstream from the lower axis. No samples from these de- posits have been tested, but they are probably suitable for use as pervious fill. The average haul distance for this group of deposits is approximately 2 miles from the lower axis, measured along the stream channel. Based on an average depth of 3 yards, the volume of this group of deposits is conservatively estimated to be 888,000 cubic yards. This area is not designated on Plate C3° C-26 The combined volume of the latter three groups of pervious materials is 4^27^^000 cubic yards. Impervious or Random Fill Deposits in Wilson Valley were sampled and found suitable for use either as impervious fill or properly drained random fill. Approximately 8,500^000 cubic yards of this material are estimated to lie within Wilson Valley . The average haul distance for these deposits is approximately 2 miles from the lower site measured along the dirt road between Wilson Valley and the lower dam site For the location of these materials see Plate C3« An additional probable source of impervious material is the silty phase of the Cache formation. This formation outcrops in the spillway area of the upper site and northwest of Wilson Valley. Riprap Sufficient riprap material can probably be obtained from peridotite bodies outcropping along Rocky Creek approximately 2 miles west of the dam sites. The exact limits of the outcrops cannot be ascertained until additional exploration is conducted. For the loca- tion of riprap materials see Plate C3. Summary 1. Both abutments and the spillway of the lower site are underlain by relatively impervious siltstones, mudstones, and minor sandstones of the Knoxville group of Upper Jurassic age. These sedi- ments dip steeply upstream. 2. The channel section of the lower site is filled with an average thickness of 15 feet of stream channel deposits which must C-27 be removed . An additional 15 feet of bedrock below this should be removed. 3. Stripping of approximately 10 feet of the upper por- tions of both abutments and approximately 40 feet under the impervious core area should expose suitable foundation material for the proposed earthfill dam at the lower site. Approximately 10 feet of unsuitable material would have to be excavated from any spillway located on the left abutment. However, depth and amount of excavation for a spill- way through the saddle northeast of the left abutment would be con- siderable. These spillway cuts should be stable at slopes of 1:1. Due to the extreme depths of cut necessary to reach the spillway lip, benches at regular intervals might prove essential. 4. Ample quantities of fill materials can be obtained within a maximum distance of 11 miles upstream from the lower site along North Fork Cache Creek and 4 miles downstream from the lower site along Cache Creek. Aggregate materials are available in this same general area, but they must be sampled and tested more extensively to determine their suitability for concrete aggregate. Riprap may be obtained from peridotite outcrops along Rocky Creek approximately 1.5 miles west of the dam site. C-28 CHAPTER III. GEOLOGY OF GUINDA DAM SITE The following discussion of the geologic characteristics of the Guinda dam site is based on data from prior reports and on field investigation by the Department of Water Resources which in- cluded surface geologic mapping,, subsurface exploration, and mate- rials sampling and testing,, General Geology The geologic formations in and adjacent to Capay Valley include sedimentary rock types which range in age from Cretaceous to Recent, Sandstone and shale of Cretaceous age extend beneath the entire area, and are overlain locally by semi-consolidated Tertiary sediments, by unconsolidated Pleistocene terrace gravels, and by Recent alluvium as shown on Plates C5 and C6. The Chico group of Cretaceous age, as described by J, M, Kirby in his "Rumsey Hills Area" report, is the oldest lithologic unit in the area and includes alternating beds of marine sandstone and shale. The sequence is occasionally broken by beds of conglom- erate. In general, the sandstone and conglomerate strata are thickly bedded, hard, and well cemented except on weathered sur- faces where these rocks become friable. The shale strata are usually thinly bedded and highly fractured. Thickness of the Chico group in this area is approximately 12,000 feet Overlying the Chico group and outcropping along the west- ern flank of Capay Valley is the Capay formation of Eocene age. This was established by Crook and Kirby in their investigations. Rock units in this formation consist of a brown colored, tough marine clay shale with interbedded hard, well-cemented and gray C-29 micaceous sandstone. The shales characteristically are thinly bedded., somewhat fractured, and have an uneven bedding surface . Thickness of this formation reaches a maximum of 2,500 feet in the area southwest of the town of Guinda. The Tehama formation of Plio-Pleistocene age overlies the Capay formation and the Chico group as pointed out by Kirby. This formation underlies all of the valley floor and outcrops along the eastern and western flanks of Capay Valley,, The Tehama formation consists of non-marine clay, clayey and sandy silt, sand, gravel, conglomerate, marl, and limestone. The finer grained sediments are red-brown or pale buff. Sand, silt, and clay which make up the major part of the formation in this area are commonly massive and show little structure. The formation attains a maximum thickness of 1,500 feet on the east flank of the Rumsey Hills according to J. M. Kirby . It is probably 1,000 to 1,500 feet thick in the trough of Capay Valley, Pleistocene and Recent unconsolidated sediments cover the valley floor and overlie the Tehama formation. The Pleistocene sed- iments are stream terrace deposits ranging in size from small gravel to boulders. Voids are generally filled with a reddish matrix consisting of sand and silt. At least four terrace levels have been formed by the erosive action of Cache Creek. The gravels attain a maximum thickness of 45 feet adjacent to the right abutment of Guinda dam site. Recent alluvium along the active channel of Cache Creek occurs as sand and gravel bars and undifferentiated flood plain deposits. Cache Creek, in the area of the Guinda dam site, has cut through the Pleistocene terrace gravels and is now entrenched in the Tehama formation. The alluvium, consisting of unconsolidated gravel, sand, and silt, is a thin deposit and for the greater part immediately overlies the Tehama formation. C-30 Structurally, Capay Valley is a broad, elongated, synclinal valley in the southeast portion of the Northern Coast Ranges geomor- phic province. Capay Valley, which is approximately 16 miles long and ranges in width from 1 to 2 miles, is bounded on the east by the Rumsey Hills which represent the surface expression of an asymmet- rical anticline . West of Capay Valley the strata are homoclinal, and generally display an easterly dip Minor folds are also present, and will be discussed under geology of the dam site. The major known faults in the area, first mapped by Kirby, are the Sweitzer fault and the Eisner thrust fault, as shown on Plate C5. Both structures occur on the western limb of the Rumsey Hills anticline at an elevation well above the top of the dam and spillway area,. The Sweitzer fault forms a prominent escarpment along the western flank of the Rumsey Hills and extends for nearly their entire length. The Eisner fault is a short, low angle thrust fault occurring only between the small towns of Guinda and Rumsey. Due to a westerly movement along this fault, nearly horizontal Cretaceous sediments have been thrust over vertical Cretaceous sediments as well as over gravels in the Tehama formation. The presence of the Sweitzer and Eisner faults in the left abutment area will not constitute a problem as far as stripping or grouting is concerned as the surface trace of the Eisner fault, which is the lower of the two faults, is approximately 0.5 mile east of the left abutment and approximately 150 feet in elevation above the proposed crest of dam. Geology of Dam Site Foundation rock at the proposed dam site consists of consolidated sandstone and shale of the Capay formation of Eocene C-31 age overlain by semi-consolidated sandy and clayey silt, the conglom- erate of the Tehama formation,, and by unconsolidated Pleistocene and Recent sediments in the valley floor. Consolidated sandstone and shale of Cretaceous age underlie the proposed dam site at consid- erable depth beneath these younger sediments. Left Abutment The Tehama formation of Plio-Pleistocene age forms the foundation rock of the entire abutment, as is shown on Plates C5 and C6 Consolidated sandstone and shale of Cretaceous age underlie the Tehama at considerable depth. The lithologic units exposed include a thin cemented conglomerate overlain by a thick section of compacted silts. The conglomerate outcrops in essentially horizontal beds at the base of the abutment and extends upward to a height of approx- imately 60 feet. The gravels were probably laid down in a shallow stream bed and later cemented by calcium carbonate into conglomerate. This portion of the abutment would probably accept a moderate amount of grout. Overlying the conglomerate and extending upward to and above the top of proposed dam is a silty phase of the Tehama forma- tion. This material represents a weathered phase of the silt sim- ilar to that cored in the six test holes in the valley fill, and comprises clayey silt and clay, stringers of marl, and occasional sand and gravel lenses. Structurally, the left abutment is near the crest of a small asymmetrical anticline as shown on Plate C6„ The west limb of this fold has been partially removed by erosion and covered by C-32 Pleistocene gravels at the base of the abutment adjacent to Cache Creeko East of the crest of the anticline the Tehama formation dips to form a small syncline. The saddle east of the right abutment is probably a topographic feature developed along this syncline. The eastern limb of this syncline is steeply inclined and has a westerly dip of approximately 60°„ Right Abutment The Tehama formation forms the foundation rock of most of the right abutment „ These deposits,, similar in lithology to the left abutment^, probably occur as a relatively thin layer over the under- lying Capay formation of Eocene age. The underlying Capay formation., which outcrops high on the abutment,, is predominantly a cemented gray micaceous sandstone and brown clay shale. The Capay and Tehama formations in the abutment dip gently to the east in a uniform homoclinal dip. Immediately west of the abutment the Capay formation dips to the west,, indicating the presence of an anticlinal fold in the abutment area. Channel Section Pleistocene terrace deposits and the underlying Tehama formation form the foundation rock of the entire channel section^ as shown on Plate C6. Recent alluvium occurs in the present stream channel of Cache Creek. The Tehama formation underlies the valley floor at shallow depth and may be in the order of 1^000 to 1^500 feet in thickness, A seismic profile normal to Cache Creek was made of the Guinda dam site by the Department of Water Resources. The purpose C-33 of this survey was to obtain data on foundation conditions at this site and to aid in the selection of locations for test holes . The thickness of the alluvial fill in the valley was thought to be large, but it was hoped that an impervious clay layer, which might serve as a satisfactory foundation, might be found „ The seismic method determines differences in the speed of shock wave transmission of the various materials underlying the ground surface. Because of this varying transmitting capacity of different lithologic units, it is possible to compute their thickness. This method, however, is not capable of ascertaining directly the lithologic nature of the material being investigated, nor is it ca- pable of determining the thickness of the lowest stratum studied. The seismic survey indicated the presence of several hori- zons at shallow depth. A horizon is defined as a layer of homoge- neous material differing from that found above and below it. The thickness and physical character of these horizons could not be deter- mined by the survey. An upper horizon was continuous across the val- ley to the west of Cache Creek. Thickness of overlying material was 50 to 60 feet over the westerly half of the valley, and decreased gradually to about 10 feet over the easterly half. A second horizon was also indicated beneath Cache Creek at a depth of about 30 feet. This horizon was traced about 700 feet to the west of Cache Creek and about 150 feet to the east of the creek. It was not possible to determine if this second horizon was continuous beneath the first horizon. Cores obtained from six test holes drilled across the valley show the Tehama formation to consist predominantly of compact red-brown sandy and clayey silts and clays, usually containing black C-34 carbonaceous fragments and a variable amount of calcium carbonate as small concretions. Frequently the silts graded into a highly calcar- eous silt or clay forming a material commonly referred to as marl. Thin gravel and sand bodies saturated with water occur in the Tehama formation beneath the valley surface. They may contain confined water as indicated in test hole No, 6. There is no information avail- able as to the possible outcrop area of these saturated sand and gravel lenses in the reservoir area or in the valley floor downstream from the dam site. Gravels and sands cemented with calcium carbonate are also present but are localized in occurrence. In general, the material encounted in the upper part of the Tehama is a compact silt with varying amounts of clay and sand, and is similar to the unweath- ered silty sediments in the right and left abutments and in the spillway section. However, in test hole No. 5* a large portion of the material recovered was loose water-bearing sand and gravel from a depth of 18 to 48 feet. Below this depth a greater amount of compact, relatively impermeable material was recovered. Deformation due to probable folding and/or faulting in the Tehama formation is manifest in shears found in cores from three of the six test holes, Nos. 1, 4, and 6. Evidence of shearing is minor in all but one test hole -- test hole No. 1 adjacent to the right abutment ~ where Tehama silts are badly sheared and highly fractured from 14 feet to 38 feet in depth. Only four shears were found below 38 feet. Either sharp folding or faulting may be responsible for the fractured and sheared condition of the rock here. Further ex- ploration would be necessary to establish the type and extent of this deformation. Overlying the Tehama formation are Pleistocene terrace gravels which vary in thickness from to 45 feet. Although no C-35 cores were obtained from these terraces, drilling evidence indicated that very coarse material and permeable zones exist down to the Tehama formation. These terrace deposits are composed of gravels ranging in size from pebbles to boulders. This coarse material is in a matrix consisting of sand, silt, and clay. Results from soil tests indicate that a large portion of this material could be used for fill material. Although the material sampled contains a large percentage of fines, which would reduce the permeability, test hole data and some expo- sures of these terrace deposits indicate that it is locally permeable, and hence a cutoff to the Tehama formation is believed to be desir- able. An unknown thickness of Recent alluvium underlies the present stream channel of Cache Creek. These unconsolidated alluvial deposits in the stream channel consist of sand and sandy silt with interbedded rounded gravel and boulders. Soil tests indicate these deposits are suitable for use as gravel drains. Stripping Estimates The following stripping estimates are based on visual ob- servations of the material exposed, and on material recovered from auger holes and test pits. The estimates given below are for a homogeneous earthfill dam. Depths of stripping are estimated normal to the ground surface. Tehama conglomerate occurring at base of the left abut- ment extends up the slope to elevation 430 feet, or to a height of 60 feet. A silty phase of the Tehama formation overlies these C-36 conglomerates and extends to the top of the abutment. It would be necessary to strip 2 to 3 feet of conglomerates and 3 to 5 feet of Tehama silt to remove the weathered zone. On the right abutment it would be necessary to strip approx- imately 3 to 5 feet on the entire slope „ This should remove the weathered zone and expose suitable foundation material. On this abut- ment the Tehama may be thin and overlie an old weathered surface of the Capay formation. Therefore, further stripping might be nec- essary. Valley width between abutments is approximately 1-1/3 miles. The channel section is filled with a maximum of 45 feet of Pleistocene terrace gravels with a probable average thickness of 20 feet An un- known thickness of unconsolidated Recent stream channel deposits underlie the present course of Cache Creek. These deposits are prob- ably thin, but there are no test hole data to substantiate this. Approximately 5 feet of soil should be stripped throughout the channel section, except where deep excavation would be necessary for a cutoff wall through the terrace deposits. Additional stripping under the cutoff section might be required adjacent to the right abutment where the Tehama formation is badly fractured below the terrace gravels „ In this area, test hole No. 1 indicates that up to 20 feet of material might have to be removed due to fracturing and shearing. Spillway A satisfactory location for a spillway for an earthfill dam at this site would be through the saddle east of the left abut- ment. Some excavation in the silty phase of the Tehama formation C-37 would be necessary,, especially at the north and south ends of the saddle. Spillway cuts should be stable at slopes of approximately 1:1. The material could easily be removed as common excavation,, The material from such excavation could probably be used as impervious fill in the dam and in the small gap occurring along the crest of the abutment „ Lining of the entire spillway and probably some type of cutoff would be necessary to prevent erosion of the soft Tehama sed- iments. Between the saddle on the left abutment and the Eisner fault to the east,, the intervening hills of relatively low relief may be overlain by a zone of slide material of undetermined thickness which could have originated from the steeper hills above the Eisner fault. This condition should not constitute a threat to the spill- way structure as the slopes are not steep and appear to be stable. The spillway should be located as close to the left abutment as pos- sible^ thereby avoiding cuts into the base of these hills. Reservoir Leakage from the reservoir would probably be small due to the fine-grained character of the Tehama formation which underlies the entire reservoir area. However,, coarse-grained members of the Tehama formation which may outcrop in the reservoir area will contin- ue to recharge the ground water basin immediately downstream from the proposed dam. Several ranches and the small community of Rumsey lie within the proposed Guinda Reservoir. Land use is predominantly orchard, with some grain. A portion of State Highway 16, where it passes through the reservoir area, would have to be relocated . C-38 Seismicity The proposed Guinda dam site is located in an area of only moderate seismic activity,, However, the following is a discussion of three shocks which occurred in the general vicinity of Winters and Vacaville that probably would have been damaging to some structures such as canals and perhaps to the earth dam. This information was obtained from the "Earthquake History of the United States "„ Inten- sities listed in Roman numerals correspond to the Rossi-Porel Scale of Earthquake Intensity „ On April 19, 1892 » the shocks varied from IX to X In Vacaville nearly all of the brick structures were wrecked, and many frame buildings were damaged Chimneys were twisted or thrown down. The loss varied from $70,000 to $150,000. In Dixon the damage was less serious, but many structures, especially schoolhouses, were badly damaged. The loss was estimated at $75* 000 „ At Winters the damage was similar to that in Vacaville and the loss was about the same. There was more or less damage at numerous other places in Solano and Yolo Counties „ One chimney toppled at Sacramento and there was slight damage at San Francisco . Fissures were found in the bed of Putah Creek o 5 mile west of Winters, and in the adjoin- ing roadway and fields . Shock was felt from Healdsburg to Fresno and east to western Nevada . On April 21, 1892, the shocks varied from IX to X. Total energy was probably less but the intensity was as great as the shock of April 19. The most severe shock was at Winters, about 12 miles north of Vacaville. Many buildings which had withstood the previous shock were leveled to the ground. On Main Street not a single building was left in habitable condition. The buildings were C-39 constructed mostly of brick or stone. At Esparto every brick chimney fell and wooden buildings were wrenched out of shape. Damage at Vacaville and Dixon was not great. Many chimneys were wrecked at Sacramento and there was other small damage. There were varying degrees of damage in Solano., Yolo, Sonoma , Napa, Contra Costa, Butte, Nevada, San Joaquin, and Yuba Counties. The shock was felt with an intensity of V at Red Bluff to the north, at Reno to the east, and with a lesser intensity at Fresno to the south. On May 19, 1902, a shock with maximum recorded intensity of VIII occurred. The intensity was VII at Elmira, where nearly all chimneys fell; VII to VIII at Vacaville, where some chimneys tumbled; VII at Fairfield and Suisun; and V at San Francisco. The area of perceptibility exceeded 20,000 square miles, based on incomplete reports. The locations of the shocks felt in the vicinity of Winters and Vacaville are approximately 30 to 40 miles, respectively, from the dam site. However, due to the relatively unpopulated nature of the area at that time, complete reports are not available. Although no epicenters have been recorded in the immediate vicinity of the dam site, it is reasonable to assume that this area could be subjected to earthquakes of considerable intensity. Suitability of Site This site appears to be suited to only an earthfill type dam. The foundation material is probably susceptible to some set- tlement] therefore precluding the construction of a masonry type dam. Preliminary tests indicate that the terrace deposits and the Tehama formation would form a suitable foundation for the earthfill dam under consideration. c-4o Construction Materials The terrace deposits in the reservoir area should provide ample quantities of fill material for the proposed type of dam. Approximately 500 acres in the immediate vicinity of the dam would yield about 11,500,000 cubic yards if stripped to a depth of approx- imately 15 feet. Select borrow material for the core of the dam may be found in the Tehama formation east of Cache Creek and within 1 mile up- stream from the site. Excellent exposures of this material can be found at "Blue Slides", 1.5 miles southeast of Rumsey. Within 2.5 miles upstream of the proposed axis, approximately 500,000 cubic yards of stream channel gravels are available and are apparently suitable for use as gravel drains. Riprap may be obtained from the Upper Cretaceous sandstone which is exposed in the adjacent hills approximately 2 miles upstream from the axis. Moderate loss may be expected in quarrying this mate- rial due to the interbedded shale and fractured sandstone member. Soil Tests Soil samples were obtained and tests were conducted to determine the character of the construction and foundation materials. Results from these tests were utilized to develop the engineering designs and the estimates of the proposed Guinda dam. A complete explanation of these tests is presented in the geologic appendix of the report entitled, "Interim Report - Cache Creek Investigation, March, 1955". C-4l 1. Both abutments and the spillway are underlain by slightly to moderately compacted silts, clay silts, and marls with sand and gravel lenses of the Tehama formation of Plio-Pleistocene age 2. The channel section is underlain by an average of 20 feet of unconsolidated sand and gravel river terrace deposits with a maximum depth of 45 feet. A large volume of the terrace deposits would have to be removed for the placement of the desired cutoff to the Tehama formation. Test hole drilling indicates the top of the underlying Tehama formation may be permeable in places and sheared near the right abutment, thus requiring additional excavations. 3. Stripping of 3 to 5 feet on both abutments and spill- way will remove the weathered and root zone. 4. Terrace deposits should provide ample quantities of fill material for the proposed type of dam. Select borrow for the core may be obtained from the Tehama formation. 5. Sufficient stream channel deposits for use as gravel drains may be obtained within 2.5 miles of the proposed axis. The Upper Cretaceous sandstone should provide suitable riprap. C-42 slij sane fee' max: WOUL the und( nea: way fii: core dra: Upp< J I I I I l_ L I I I L LENGTH IN FEET SECTION B-B' LOWER SITE, WILSON VALLEY DEPARTMENT OF WATER RESOURCES CACHE CREEK INVESTIGATION GEOLOGI \o- \ \ irrrni \ DEPARTMENT OF WATER RESOURCES CACHE CREEK INVESTIGATION POSSIBLE SOURCES OF CONSTRUCTION MATERIALS WILSON VALLEY DAM SITE APRIL 1958 L MONTtCELLO SANTA ROSA Doia from us Coos! ond Geodetic Survey Report 37 INTENSITY - CORRESPONDING TO ROSSI-FOREL SCALE OF EARTHQUAKE INTENSITY O INTENSITY ■ LOCAL, CORRESPONDING TO R F SCALE EPICENTER OF EARTHQUAKE WAS 38° 56' NORTH, 122° 52' WEST SHOCKS WERE FELT AT 03:50:39 PST. STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING CACHE CREEK INVESTIGATION ISOSEISMAL MAP FOR EARTHQUAKE OF MAY 7, 1955 SCALE OF MILES DEPARTMENT OF WATER RESOURCES. 1958 PLATE C5 STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING CACHE CREEK INVESTIGATION GEOLOGY OF RESERVOIR AREA AND LOCATION OF SOIL SAMPLES GUINDA DAM SITE 1953 SCALE OF MILES DEPARTMENT OF WATER RESOURCES 1956 PLEISTOCENE JQf, I, 2,3] Gr _, el ,„„ „„, "' pliocene I Tp, I K~£{»;y TEST MOLES 4800 DISTANCE IN FEET GEOLOGIC SECTION A- A' [ 1 ^ ALCAftEOUS SILT 1 © MOBIZONT. \!5- STRIKE AMI «<■»• STBIKE AN "f „ E ~ f._,™cu« ' INDEFINITE CONTACT O EXPLORATION AUGER HOLES T7f TEST HOLE O TE3T PIT ^^" ^" T HRU5T FAULT lappro"ma1e lacaljAiJ 'MZZZtitz TOP SOIL STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING CACHE CREEK INVESTIGATION SURFACE AND SUB-SURFACE GEOLOGY AND LOCATION OF TEST HOLES GUINDA DAM SITE 1953 DEPARTMENT OF WATER RESOURCES 1956 APPENDIX D COURT DECREES D-l TABLE OF CONTENTS Page ji5Gnuri"x -x.,y i/coi c^«oo«oo*oooeo«o»ooo««o**« x-/ ~ ^? D-2 COPY IN THE SUPERIOR COURT OF THE STATE OF CALIFORNIA, IN AND FOR THE COUNTY OF MENDOCINO ) DECREE M. M. GOPCEVIC, and THE HOTALING ESTATE CO., a corporation, and GEORGE T. RUDDICK, Plaintiffs, vs. YOLO WATER AND POWER COMPANY, a corporation, and YOLO WATER AND POWER CORPORATION, a corporation, Defendants, COUNTY OF LAKE and LISLE STUBBS et al, Intervener Pursuant to the stipulation of all parties herein reduced to writing and filed in open court on the 7th day of October, 1920, agreeing and consenting that the following judgment and decree be entered in the above entitled action, and upon evidence taken; and finding being waived in open court by all parties; IT IS HEREBY ORDERED ADJUDGED AND DECREED AS FOLLOWS: That the defendant herein be perpetually enjoined and restrained from excavating or deepening the outlet of Clear Lake, being the Clear Lake mentioned in the pleadings herein, to any depth greater than four feet below the zero mark on the Rumsey gauge at Lakeport, County of Lake, State of California, which said gage is hereinafter more particularly referred to; and from widen- ing straightening or otherwise interfering with said outlet, except D-3 as may be necessary to carry out the provisions of this decree,, all of such work to be with the approval first obtained and under the super- vision of the State Railroad Commission of California, or the members thereof j and this injunction shall include the said defendant s, their and either of their, officers, agents, servants, employees successors and assigns, and each and all officers and agents of either of them, and all persons acting under or in aid of them or either of them. That the agents, servants, employees, successors and assigns of the said defendants and the said defendants and each of them, and all persons acting under or in aid of them or either of them be perpetually enjoined and restrained from at any time, or in any way raising the level of said lake in excess of 7.56 feet above zero on said Rumsey Gauge, and from at any time or at any way lowering the level of said lake below zero on said Rumsey Gauge; provided, however, that the rise of said Clear Lake, by reason of storm or flood condi- tions beyond the control of said defendants, or either of them, to a level in excess of 7.56 feet above zero en said Rumsey Gauge, but in no event to a level in excess of 9.00 feet above zero on said Rumsey Gauge, for any period not exceeding ten successive days, shall not be deemed a violation hereof; The zero mark on said Rumsey Gauge is 20.1 feet below cen- ter of large concrete star in northeast corner of court house yard at said Lakeport, and 21.56 feet below iron step at front enterance to Bank of Lake Building at southeast corner of Main Street and Sec- ond Street, in said Lakeport; That said defendants, and each of them, their officers, agents, employees, successors and assigns and all persons acting D-4 under or in aid of them or either of them, be perpetually enjoined and restrained from drawing off from said Clear Lake an amount of water which, inclusive of evaporation and other losses, will at any time reduce the level of said lake below zero on said Rumsey Gauge] and the said defendants, and each of them, their officers, agents, employees, successors and assigns, be perpetually enjoined and com- manded to draw off from said lake an amount of water which, inclus- ive of evaporation and other losses will reduce the level of the lake so that the elevation thereof on the following dates shall not exceed the following percentages of the actual level on April 15th of each year; May 1, 97$, June l 89$, July 1, 79& August 1, 69$ and September 1, 58$ „ That said defendants and each of them, their officers, agents, employees successors and assigns, be perpetually enjoined and restrained from drawing off from said lake, during the irrigation season an amount of water which, inclusive of evaporation and other losses shall lower the level of said lake more than two feet in any one month ; It is hereby specially adjudged and decreed that not- withstanding the limits of depression of said lake waters herein- above described the said defendants, and each of them, their agents, employees, successors and assigns, shall not draw off or allow, and they and each of them are enjoined and restrained from drawing off or allowing the waters of said lake to flow out of said lake at any time at such a rate as that, taking into account evaporation and other losses, the water of said lake shall at the lowest level of any year be below zero on said Rumsey Gauge; D-5 It is further adjudged and decreed that the said defendant s, or either of them, shall at or about the specific dates last herein- above mentioned, notify in writing., through the mails or otherwise, the parties hereto and as well such owners or occupants of land on the rim of said lake as shall register their names and addresses with the defendant, Yolo Water and Power Company, at its office in Woodland, Yolo County, California, of the then existing and respective levels of the said lake* The drawing off of the water of said lake under the condi- tions aforesaid, shall be by and through the dam and gates mentioned in the pleadings herein, and the administration conduct and operation of said dam and gates shall be responsive to and in full and fair execution of such conditions, and shall at all times be by and under the State Railroad Commission of California, or the members thereof; If at any time the injunctive provisions of this decree shall be violated, or departed from in matter of substance and all the provisions of this decree are for this purpose taken to be in- junctive then and in such events the said defendants and each of them are hereby enjoined and commanded forthwith thereupon, in the manner and to the extent hereinafter provided, or in default thereof it shall be competent to the plaintiffs or any or either of them, or in default of action in the promises by the plaintiffs or any or either of them, it shall be competent to the interveners, or any or either of them, and said parties are accordingly hereby authorized, at the expense of defendants, their successors and assigns to restore and maintain at the "Grigsby Riffle" mentioned in the com- plaint herein, but above the present mouth of "Seigler Creek" a suitable and substantial structure or barrier, the crest of which shall not exceed one foot above zero on said Rumsey Gauge except as hereinafter provided; D-6 But it is further and specifically decreed that if at any time, for any physical reason, or otherwise, said dam should cease in any substantial sense, to function in respect -co the operation of the same as hereinabove referred to, then and in that event the crest of the aforesaid structure or barrier may be increased and maintained to an elevation of two feet above zero on said Rumsey Gauge, said structure and barrier shall exist and be maintained at all times when a dam shall cease to function as provided in this decree for the op- eration of the same; provided however that the failure of the defend- ants or either of them to comply substantially with the terms of this decree, due to temporary, unavoidable causes shall not be deemed a violation of this decree; It is further adjudged that this decree does not adjudicate upon the extent of the several riparian or littoral rights of any of the parties hereto in the said Clear Lake or the land adjacent thereto nor upon any rights or claims of any of said parties to water rights therein, nor in or over such adjacent lands, and that the injunctive relief hereby granted and provided for Is not based upon a waiver by any of said parties of any such substantive rights of claims afore- mentioned but is subject to full reservations on the part of all and each of said parties of all said substantive rights or claims aforesaid; It is further ordered adjudged and decreed that the said dam and the operation thereof shall at all times be subject to rea- sonable access and inspection by the parties hereto as well as any person owning land riparian or littoral to said Clear Lake and their duly authorized agents or attorneys; but if any question should arise in respect to the right of any such person or persons to such access and inspection, the same shall be remitted to the state railroad commission of California, or the members thereof for final deter- mination; D-7 That all claims for damages involved in this action or on account of the issuance of the temporary restraining order or prelimi' nary injunction herein are waived and adjudged to be fully settled; That each party to this action shall pay his own costs. The signing and filing of this decree shall be deemed to be noticed of the terms thereof and effective as service of any in- junctive process consequent thereon. Done in open Court the 7th day of October, 1920. A. B. McKenzie Judge. CERTIFIED ENDORSED : RECORDED: October 7th, 1920, by the Clerk of said Court to be a full, true and correct copy of the original on file and of record in his office. Filed Oct. 7, 1920, HALE PRATHER, Clerk By W. H. PRATHER, Deputy October 8th, 1920, in Vol. 60 of Deeds, at page 49. Records of Lake County, California D-8 C. C. McDonald, Attorney for Plaintiffs, Woodland, California IN THE SUPERIOR COURT OF THE STATE OF CALIFORNIA, IN AND FOR THE COUNTY OF YOLO, MARY E. BEMMERLY AND AGNES R. BEMMERLY, Plaintiffs, vs THE COUNTY OF LAKE, a Political Subdivision of the State of California, E. L. HERRICK, W E REICHERT L. D c KTRKPATRICK, L. L BURGER AND J. S. KELSAY, as and comprising the Board of Supervisors of the County of Lake, State of California, THE BOARD OF SUPERVISORS OF THE COUNTY OF LAKE, STATE OF CALI- FORNIA, E c L e HERRICK, individually and as a member of the Board of Supervisors of the County of Lake, State of Cali- fornia, FRANK W NOEL, individually, W E„°REICHERT, as a member of the Board of Supervisors of the County of Lake, State of California, W T e SMITH, individually, L D. KIRK- PATRICK, as a member of the Board of Supervisors of the County ^ of Lake, State of California, L L. BURGER, individually and as a member of the Board of Supervisors of the County of Lake, State of California, J S. KELSAY, individually and as a mem- ber of the Board of Supervisors of the County of Lake, State of California, FRANK B„ JOHNSON, individually and as a County Surveyor of the County of Lake, State of California, FRANK W. CLARK as Director of the Department of Public Works of the State of California, CLEAR LAKE WATER COMPANY A CORPORATION, J„ R, REEVES, JOHN DOE DREDGING COMPANY, RICHARD ROE DREDGING C0 o5 FIRST DOE 9 SECOND ROE AND THIRD ROE, No. 8812 o p Defendants JUDGMENT This cause having beer, regularly called and tried by the Court, and the findings of fact and conclusions of law, and the de- cision thereon in writing, having been rendered, wherein judgment was ordered in favor of the plaintiffs and against the defendants hereinafter named as prayed for in the complaint and for costs, D-9 IT IS, BY THE COURT, ORDERED, ADJUDGED AND DECREED that the defendants, The County of Lake, a Political Subdivision of the State of California, E D L. Herrick., W„ E. Reichert, L. D. Kirkpatrick, L. Lo Burger and J c S a Kelsay, as and comprising the Beard of Super- visors of the County of Lake, State of California, the Board of Supervisors of the County of Lake, State of California, E L. Herrick, individually and as a member of the Board of Supervisors of the County of Lake, State of California, Prank W. Noel, individually, Wo E„ Reichert as a member of the Board of Supervisors of the County of Lake, State of California, W 6 T„ Smith, individually, L c D. Kirk- patrick as a member of the Board of Supervisors of the County of Lake, State of California, L. L. Burger, individually and as a member of the Board of Supervisors of the County of Lake, State of California, Jo So Kelsay, Individually and as a member of the Board of Super- visors of the County of Lake, State of California, Prank B c Johnson, individually and as County Surveyor of the County of Lake, State of California, Prank W 6 Clark, as Director of the Department of Public Works of the State of California, and Clear Lake Water Company, a corporation, and each and all of them, and their, and each of their attorneys, agents, servants and employees and any and all persons acting under said defendants, or any of them, be, and they and each and all of them are hereby forever enjoined and restrained from in any manner widening, deepening or enlarging the arm or slough which constitutes the outlet of the waters of and from Clear Lake into Cache Creek and from in any manner changing the said outlet so as to increase the flow of waters of and from Clear Lake into Cache Creek. The Clear Lake herein referred to is the Clear Lake de- scribed in the plaintiffs' complaint and which is located in the County of Lake, State of California. D-10 IT IS FURTHER ORDERED., ADJUDGED AND DECREED that plaintiffs have judgment for their costs taxed at Dollars ($ ). Judgment rendered December 18th, 19^0 /s/ Dal M. 'Lemmon Judge of the Superior Court D-ll APPENDIX E SUPPLEMENTAL AGREEMENT BETWEEN STATE WATER RESOURCES BOARD, COUNTY OF YOLO, AND DEPARTMENT OP PUBLIC WORKS, DATED SEPTEMBER 26, 1955 E-l SUPPLEMENTAL AGREEMENT BETWEEN THE STATE WATER RESOURCES BOARD , THE COUNTY OF Y0L0 5 AND THE DEPARTMENT OF PUBLIC WORKS THIS SUPPLEMENTAL AGREEMENT, executed in quintuplicate, entered into as of the 26th day of September, 1955, by and between the State Water Resources Board, hereinafter referred to as the "Board", the County of Yolo, hereinafter referred to as the "County", and the Department of Public Works, State of Cali- fornia, acting through the agency of the State Engineer, herein- after referred to as the "State Engineer" : WITNESSETH WHEREAS, an agreement entered into as of the 7th day of May, 195^* by and between the parties hereto., provided for (l) review of reports of prior investigations of the water resources of Cache Creek watershed and potential service areas in Yolo County, (2) investigations and studies to determine present water utilization and potential service areas for Cache Creek water in Yolo County, the water resources thereof, ultimate irrigable land, water requirements, preliminary plans and esti- mates of costs for control, development and utilization of said water resources, and preparation of a report thereon; and WHEREAS, by said agreement the Board authorized the State Engineer to conduct said investigation and prepare said report; and E-3 WHEREAS, the expense of performing the aforesaid work was estimated to be approximately $24,000 of which sum one half was contributed by the County and the remaining one half by the State of California; and WHEREAS, work on the aforesaid review and investigation was initiated and an interim report thereon, dated March, 1955, was prepared by the State Engineer, transmitted to the Board, and was approved and transmitted by the Board to the California Legis- lature," and WHEREAS, Section 12663 was added to the Water Code by Chapter 1950, Statutes of 1955^ which section adopts the plan of improvement for flood control and water conservation on Cache Creek, including Clear Lake, in Yolo and Lake Counties, and authorizes the same generally in accordance with the plans and recommendations relating thereto contained in the aforesaid interim report, and which section further provides that no funds shall be expended on planning or constructing a dam at the Guinda site below Rumsey on Cache Creek until the Wilson Valley area has been completely investigated and studied, and determined by the Board not to have comparable engineering and economic feasibility as compared to the Guinda site as recommended in said report; and WHEREAS, it is estimated that approximately $45,000 will be required to fully perform the additional work called for by the aforesaid legislation, and no funds are presently available for such purpose on behalf of the State of California and cannot be made available prior to the next session of the Legislature; and E-4 WHEREAS, the County desires prompt performance and completion of the work called for by the aforesaid legislation in order that the continuing water shortage in the County may be alleviated at the earliest possible time; NOW, THEREFORE, in consideration of the premises , it is mutually agreed by the Board, the County, and the State Engineer as follows : ARTICLE I— WORK TO BE PERFORMED The work to be performed under this agreement, to the extent funds are made available therefor, shall consist of a complete investigation and study of the Wilson Valley area in accordance with the requirements of Chapter 1950,, Statutes of 1955* and will include hydrologic studies of runoff and yields of reservoirs coordinated with the operation of Clear Lake, studies of flood control benefits, geologic studies, collection and laboratory testing of construction and foundation materials, ex- ploration of foundations by drilling, estimates of costs of rights- of-way and highway relocation, preparation of designs and cost estimates of dams and reservoirs at the Wilson Valley sites, economic and engineering comparison with a dam and reservoir at the Guinda site on Cache Creek, and preparation of a report on the investigation The Board by this supplemental agreement authorizes and directs the State Engineer to cooperate by conducting said inves- tigation and preparing said report and by otherwise advising and assisting in formulating solutions to the water problems in Yolo County E-5 During the progress of said investigation, all maps, plans , information, data, and records pertaining thereto which are in the possession of any party hereto, shall be made fully available to any other party hereto for the due and proper accom- plishments of the objectives hereof The work to be done under this agreement shall be diligently prosecuted with, the objective of completing the inves- tigation and report by April, 1957s or as nearly thereafter as possible,, ARTICLE II- -FUNDS On execution of this agreement, the County shall trans- mit the sum of Twenty-Two Thousand Five Hundred Dollars ($22,500) to the State Engineer for deposit, subject to the approval of the Director of Finance, into the Water Resources Revolving Fund in the State Treasury, for expenditure by the State Engineer in per- formance of the work provided for in this agreement. Immediately upon an appropriation of funds to the Board by the Legislature for such purpose, the Board shall request the Director of Finance to approve the transfer of the sum of 'Twenty-Two Thousand Five Hundred Dollars ($22,500) from funds appropriated to the Board as aforesaid to the said Water Resources Revolving Fund for expen- diture by the State Engineer in performance of work provided for in this agreement, and Immediately upon such transfer and deposit in said Water Resources Revolving Fund, the money shall be avail- able for expenditure as aforesaid . E-6 It is understood by and between the parties hereto that the sum of Forty-Five Thousand Dollars ($45,000) is ade- quate to perform the above specified work It is further understood by and between the parties hereto that this supplemental agreement shall take effect as of the date of its execution and that commencement of the work pro- vided herein shall be authorized upon deposit into the Water Resources Revolving Fund in the State Treasury of the money trans- mitted by the County to the State Engineer for that purpose, notwithstanding that completion of the work will be contingent upon the appropriation of funds by the Legislature to the Board as hereinbefore set forth. It is contemplated that such appro- priation will be made, but neither the Board nor the State Engineer assumes any liability for completion of the work or for any portion of the funds already expended in the event said appropriation is not made. The Board and the State Engineer shall under no circum- stances be obligated to expend for or on account of the work provided for hereunder any amount in excess of the funds made available for such work. E-7 Upon completion and final payment for the work pro- vided for in this supplemental agreement, in the event the Legis- lature appropriates funds to the Board to be expended for perform- ance of such work, the State Engineer shall furnish to the Board and to the County a statement of all expenditures made under this agreement, and one half of the total of all said expenditures shall be deducted from the sum advanced from funds appropriated to the Board and one half of the total amount of all of said expenditures shall be deducted from the sum advanced by the County and any balance which may remain shall be returned to the Board and to the County in equal amounts,, In the event the Legislature fails to appropriate funds to the Board for expenditure in performance of the work provided for in this supplemental agreement, the State Engineer shall report on the work accomplished and shall furnish to the Board and to the County a statement of all expenditures made hereunder and the total amount of such expenditures shall be charged to the sum advanced by the County. Not withstanding anything herein contained to the con- trary, this agreement may be terminated and its provisions may be altered, changed, or amended, by mutual consent of the parties hereto. E-8 IN WITNESS WHEREOF, the parties hereunto executed this supplemental agreement as of the date first herein written c Approved as to Form and Procedure COUNTY OF YOLO /s/ Anthony B. Avilla District Attorney County of Yolo By /s/ J e W c McDermott Chairman, Board of Supervisors S E Approved as to Form and Procedure C, Lo Hiddleson Clerk, Board of Supervisors By /s/ R. J 8 Christ! son, Deputy /s/ Henry Hoi singer Attorney for Division of Water Resources MCN STATE WATER RESOURCES BOARD APPROVED AS TO FUNDS Comptroller By /s/ Clair A . Hill Clair A. Hill, Chairman S E A L DEPARTMENT OF PUBLIC WORKS FRANK B. DURKEE, DIRECTOR :S.H.Y.:J.F.M.:F.W.L,: :Form : Budget; Value sDescript, DEPARTMENT OF FINANCE APPROVED Oct 7 1955 JOHN M. PEIRCE, Director By /s/ Louis J. He Inzer Administrative Adviser By /s/ C. M. Gilliss C. M. Gilliss Deputy Director of Public Works /s/ A» D, Edmonston A, D. Edmonston, State Engineer E-9 STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING CACHE CREEK INVESTIGATION CLEAR LAKE- CACHE CREEK BASIN SCALE OF MILES DEPARTMENT OF WATER RESOURCES 1956 X */ .V X > / AXxAt •K / ',^ A \*/\ ' X-^ #\'A 'A' x IK - x \ ' \ A ** \ \ ;•■ \ C • x. - x\ \ ,--\ ^je E^ fV" A -° \ -*?' > A A^ '> A .. K J/ /• K x e y x x * x ,( ■3 /i\/ ~:y ' \ ■ >>A>1 X\X\,A^>0 #^ El- • >< * X . \ v r „ '"' "' \ / x ^ ^J^ / < ' "^ ONv — Natural Ground ~ Eicovation Line N S . n\ s : .,- -' ■-■■ . , ■' \ PROFILE OF OAM LOOKING UPSTREAM SECTION OF DAM DEPARTMENT OF WATER RESOURCES DIVISION OF RESOURCES PLANNING CACHE CREEK INVESTIGATION WILSON VALLEY DAM ON CACHE CREEK RESERVOIR STORAGE CAPACITY OF 1,000,000 ACRE- FEET DEPARTMENT OF WATER RESOURCES 1959 J PROFILE OF DAM LOOKING UPSTREAM DEPARTMENT OF WATER RESOURCE5 CACHE CREEK INVESTIGATION GUINDA DAM 1955 DEPARTMENT OF WATER RESOURCES I95S 1 // 1 1 f // // / / / /I WILSON VALLEY PROJECT STORAGE CONTROL STORAGE GUINDA PROJECT ® 1 1 1 1 / / / // // // /T // y X V WILSON VALLEY PROJECT WITH FL0O0 CONTROL STORAGE ^—^— WITHOUT FLOOD CONTROL STORAGE GUINDA PROJECT ® ^ y -^\\^ 1 1 1 1 STORAGE CAPACITY IN HUNDREDS OF THOUSANDS OF ACRE FEET Fig. I. TOTAL CAPITAL COST STORAGE CAPACITY IN HUNDREDS OF THOUSANDS OF ACRE FEET Fig. 2. ANNUAL COST / ' A A y // t ( // f [/ WILSON VALLEY PROJECT WITH FLOOD CONTROL WITHOUT FLOOO CONTROL STORAGE GUINDA PROJECT ® / 1 1 1 I / X c > / / / / / / WILSON VALLEY PROJECT With FLOOO CONTROL STORAGE CONTROL STORAGE GUINDA PROJECT ® / 1 1 1 1 1 STORAGE CAPACITY IN HUNDREOS OF THOUSANDS OF ACRE FEET FIG. 4. ANNUAL PROJECT BENEFITS STORAGE CAPACITY IN HUNDREDS OF THOUSANDS OF ACRE FEET Fig. 5. BENEFIT-COST RATIO / ;? V ^rr WILSON VALLEY PROJECT WITH FLOOO CONTROL STORAGE WITHOUT FLOOO CONTROL STORAGE GUINDA PROJECT ® ~ / / 1 1 1 1 STORAGE CAPACITY IN HUNDREDS OF THOUSANDS OF ACRE FEET Fig. 3. FIRM ANNUAL YIELD s /y ~77 7 // r f 7 / WILSON VALLEY PROJECT // WITH FLOOD CONTROL STORAGE WITHOUT FLOOD CONTROL STORAGE / i GUINDA PROJECT ® 1 1 1 1 STORAGE CAPACITY IN HUNDREDS OF THOUSANDS OF ACRE FEET FIG. 6. ANNUAL BENEFITS IN EXCESS OF ANNUAL COSTS COMPARATIVE DATA FOR WILSON VALLEY AND GUINDA PROJECTS APRIL 1958 DEPARTMENT OF WATER RESOURCES THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW BOOKS REQUESTED BY ANOTHER BORROWER ARE SUBJECT TO RECALL AFTER ONE WEEK. RENEWED BOOKS ARE SUBJECT TO IMMEDIATE RECALL LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS D4613 (12/76) 3 1175 00457 5133 173226 TD California . Dept. of Water Resources. 201 Division of Resources Planning. C2 Bulletin. no. 20 PHYSICAL SCIENCES LIBRARY Reb 12/78 cw V w m 19 H8NB 59fi ■■ H Hi bHSs ■1 MM