I2B3 DUTY OF WATER INVESTIGATIONS BV DON PL BARK IRRIGATION ENGINEER i.N T CHARGE OF IRRIGATION INVi 'GATIQNS IN IDAHO, OFFICE OF EXPERIMEN ^IONS, U S. DEPARTMENT OF A. ' TURE. (The work upon which this report is based \ done under a co-operative agreement between the Idaho State ^ard of Laud Commissioners and the Office of Experiment i PUS, United States Department of Agriculture. DUTY OF WATER INVESTIGATIONS DON H. BARK IRRIGATION ENGINEER IN CHARGE OF IRRIGATION INVESTIGATIONS IN IDAHO. OFFICE OF EXPERIMENT STATIONS, U. S. DEPARTMENT OF AGRICULTURE. (The work upon which this report is based was done under a co-operative agreement between the Idaho State Board of Land Commissioners and the Office of Experiment Stations, United States Department of Agriculture. e 3 ,^ :-*s^5 V "; , ^ DUTY OF WATER INVESTIGATION BY ! I > \' ' DON H. BARK./'' IRRIGATION ENGINEER, IN CHARGE OF IRRIG'Al^ON' 'INVESTIGATIONS lW IDAHO. OFFICE OF EXPERIMENT STATIONS, U. S. DEPARTMENT OF AGRICULTURE. The Idaho State Board of Land CommiSvsi oners entered into a co-operative agreement with the Irrigation Investi- gations of the Office of Experiment Stations, U S. De- partment of Agriculture, late in the fall of 1909 for the purpose of conducting a Duty of Water investigation in Idaho. This agreement was renewed from year to year, the investigation having been conducted uninterruptedly dur- ing the seasons of 1910, 11, 12, and 13. The agreement un- der which the investigation was carried on provided that both parties should contribute equal amounts toward the investigation; that the plans for the investigation be made and agreed upon by the Idaho State Engineer and the chief of Irrigation Investigations of the U. S. Department of Agriculture, and that the Idaho Agent of Irrigation Investigations should be charged with the carrying out of the investigation. The investigation has proved to be very popular with the irrigators of Idaho, eight of the larger ir- rigation companies of the State having contributed to the fund set aside for the purpose a total of almost f 8,000.00 during the four years in order that the investigation might be extended. The reports of the investigation have also been much sought after, the demand during the past two years having far exceeded the available supply. The fol- lowing report is based upon the results of the investigation during the four years, 1910 to 1913 inclusive, the investiga- tion having covered the greater part of irrigated Idaho dur- ing the period. "Duty of Water" is a term that is used to express the re- lationship that exists between a given quantity of irrigation water and the area of land it is made to servo. The Duty is said to be high when a given quantity of water serves a comparatively large area of land, and low when it is made to serve only a comparatively small area, i. c., the Duty is the work the water is made to do. It is evident even to 64;: REPORT OF STATE ENGINEER. those unfamiliar with irrigation that different types of land and different kinds of crops will require different ainoi^ts of water, -jand that all water rights should consist of amounts thaHt -would supply the actual requirements of .he.$oife and ; crops in question and no more. The above is correct in theory", '"for a'he present area of arid land is fully twenty times that of the irrigated land, but to work it out in actual practice is a very difficult matter. Forty years ago there was but litle irrigated land in Idaho, water was plentiful and the early settlers knew nothing of the water requirements of soils and crops. They therefore filed upon and appropriated abnormally large amounts for the irrigation of their land in order to be sure of a sufficient amount. As time passed and settlement in- creased a better knowledge of the water requirements of soils was obtained, but even as late as ten years ago there was no real definite knowledge of nor standard practice in regard to the subject. Water rights of all kinds and sizes existed. The need for definite knowledge of the proper amount of water to allot under different conditions became very urgent when the larger projects were pro- posed. It was realized that if too small an amount of water was allotted the settlers would suffer because of de- creased crop production, while if more than enough was allotted the land would become water logged and useless from over irrigation and the ultimate irrigated area would be unnecessarily reduced. There had never been a broad and comprehensive investigation of this subject and the urgent need for this knowledge as; a protection to the set- tlers and the State were the prime factors which led up to the investigation herein described. GENERAL PLAN AND METHOD OF THE INVESTI- GATION. Previous investigations of the subject were few in num- ber and rather confined in character. The majority of the investigations that had been made prior to the initiation of the investigation herein described were confined chiefly to the mere measurement of the amounts applied to crops by irrigation farmers and others. Tfhe various Western State Experiment Stations had also carried on some in- vestigations of this subject but these investigations were necessarily confined to comparatively small areas on the REPORT OF STATE ENGINEER. '65 Experiment Station Farms.- In laying plans for the pres- ent investigation it was plain to the author that if de- pendable data for use in connection with the allotment of water to large projects was to be secured (1) that an investigation of a broad character must be carried on; (2) that all of the various staple farm crops must, be included; (3) that water must be measured upon rather large tracts; (4) that only such tracts as were typical as regards soil, topography, preparation of land, etc., should be included, for the ultimate results secured must be such as< good farmers could obtain in actual practice; (5) that the mere measurement of water applied to a single tract and the yields secured from it would be insufficient data for they would throw no light upon the proper Duty, for there would be no indication as to what results might have been secured from the application of a larger or smaller quantity of water. It seemed imperative that the investigation be conducted in such a way that the results would be practical, fair, and impartial, and that they could be used with safety in de- termining the irrigation requirements of a large project. It was realized that there was a great variation Jn ^oijs and crops, and even between the irrigators themselves, as well as between different seasons^ and it seemed plain that a large number of tracts should be included, and that the investigation be made to extend over a number of years if dependable data were to be secured. It was therefore decided at the outset that the investiga- tion should include all of the staple farm crops common to South Idaho, and that the water should be measured upon comparatively large areas. Tfracts consisting of ap- proximately 15 acres were fixed as a basis, .care being used to select only such tracts as had uniform soil conditions, stand of crop, and previous preparation throughout. It was decided to include only typical tracts selected from average farmers- farms, and that each 15 acre tract, when- ever possible, should be divided into three parts, that the farmer or owner should be allowed to select one of the three plots into which his tract was divided and to irrigate it during the season according to his own ideas, following his usual custom in regard to the time and amount of irrigation. The amount applied by the owner was to.]b,e measured very carefully by one of the author's assistants each time the land was irrigated, and the other two plots 66 REPORT OF STATE ENGINEER. were to be irrigated during the season by applying a greater amount to one and a less amount to the other than the owner used upon the plot which he himself had selected. Thus there were in almost every case three tracts of the same crop, each tract consisting of an area of about 5 acres with uniform soil conditions and previous preparation throughout, to which three different amiounts of water were applied during the season. The water applied to and wasted from the tracts, the areas and yields, were all very carefully determined, and it was rather easy to decide in the fall from the yield produced which tract had received the best amount of water for the soil and crop in question. A portion of the experiments included in the investigation has been made at the Gooding Experiment Station, this station being conducted jointly by the Irrigation Investi- gations and the Idaho Experiment Station of the State Agricultural College. Scope of Investigation. The investigation has covered the seasons of 191 0, 1911, 1912, and 1913, during which time water has been meas- ured accurately upon a total of approximately 529 indivi- dual plots or tracts, ranging in size from .10 of an acre up to over 150 acres, and consisting of a total area of slightly over 3,600 acres. All of the areas involved have been care- fully surveyed with a transit, and the measurement of the water applied to over two-thirds of the tracts experimented upon, has been made by our own assistants, who have been on the ground during the entire time of each irrigation. The water applied to the remainder of the tracts included in the investigation has been measured, (1) by automatic water registers, (2) by the owners themselves, or (3) by an assistant who, during the season of 1912, was employed to read a large number of weirs twice daily. The results secured from a small proportion of the ex- periments have been found to be in error, due to accidents and a variety of other unavoidable circumstances. These have been discarded and nothing has been included in this report that is not absolutely dependable. The investigation has covered a wide scope of territory, the experiments having been scattered from Weiser, with an altitude of 2,114 feet, situated on the bank of Snake River on the Oregon Line, to Rigby, with an altitude of 4,950 feet, in the upper Snake River Valley, 350 miles east- ward from Weiser. REPORT OF STATE ENGINEER. 67 Alfalfa, clover, pasture, oats, wheat, barley, rye, pota- toes and orchard, the staple crops of South Idaho, have all been represented, but the majority of the experiments have been conducted with alfalfa and the grains. The average soil of South Idaho is a "lava ash" or me- dium clay loam, rich in lime and mineral plant foods, but deficient in nitrogen in its raw state. This soil ranges in depth from two to forty feet, with a probable average of slightly over four feet, and is well adapted for irrigation, being, as a rule, very uniform in texture and composition throughout its entire depth. While the majority of the experiments have been con- ducted upon the average soil, the investigation has covered such a large number of tracts scattered over so wide an area that nearly all types of soil ranging from the finest of adobe clays to the coarsest of gravels have been well represented. It was decided at the outset that the total amount of water that would be required by any project would depend upon the following factors : ( 1 ) Gross area of project. (2) Duty of water at the land. (3) The amount of loss that the irrigation water would be subjected to in transmitting it from the point of diver- sion to the land to be irrigated. (4) The amount of loss through both evaporation and seepage from reservoirs, if any were necessary in connec- tion with the system. (5) The proportion of a project that is ultimately irri- gated. It was therefore deemed necessary in connection with the investigation to investigate the seepage losses of typical Idaho canals and to survey a large amount of land in- cluded in well-developed typical irrigation projects to de- termine just what per cent was unirrigated. A seepage investigation was conducted during the two latter years of the investigation, 58 sections of different canals with an aggregate length of 109.2 miles having been measured in 1912, and 60 sections of different canals with an aggregate length of 178.11 miles having been measured during the season of 1913. The canals measured varied in discharge from 0.07 cu. ft. per second to over 3,190.0 cu. ft. per second, and in cross-section from 0.117 sq. ft, to 984.0 sp. ft. The survey of irrigated land for the determination of the 68 REPORT OF STATE ENGINEER. percentage of waste and non-irrigated laud in a typical pro- ject was conducted during the season of 1913. The land surveyed for this purpose consisted of a total of 16,065.21 acres, part of which was located near Kimberly, on the South Side Twin Falls Ttract, the remainder lying under the old canals in the Boise River Valley adjacent to and tributary to the town of Meridian. The land surveyed was typical in every way of the better class of Idaho irri- gated land and the results secured may be used with im- punity as a basis for other or newer projects. The investigation during the four years naturally and necessarily included the investigation of many other minor- subjects, such as deep percolation on gravelly irrigated land, a study of rotation systems and their adaptability to different conditions, a study of the cost and feasibility of lifting water by electric motors and centrifugal pumps, and practically all other minor factors wMch it was believed might have a bearing on the duty of water. Measurement of Water. Cippoletti weirs were used for the measurement of all water applied to the experimental tracts throughout the investigation, carefully constructed weirs having been in- stalled in the feed ditches leading to, and in the waste 1 ditches leading from, each tract for the purpose. All of the amounts tabulated in this report represent only those retained upon, or absorbed by, the tract, the waste having been deducted, unless otherwise specified. In nearly all cases the measurements were made by assistants employed especially for the purpose, it having been de- cided for obvious reasons that it would be undesirable to have the owner, or anyone who might be prejudiced in favor of a high or low Duty, connected with the investiga- tion in any way. The head on the weirs was measured by the assistant or assistants in charge of the experiments as often as was considered necessary. Where the head re- mained quite uniform it was measured at intervals of from one to two hours. Whenever the amount of water and con- sequent head on the weirs varied or fluctuated to any ex- tent the head was measured more frequently. The Cippoletti weir, designed by the Italian engineer of the same name, was used exclusively throughout the in- vestigation, great care being used to secure the proper con- ditions for accurate measurement. The formula used in REPORT OF STATE ENGINEER. 69 computing the discharge of these weirs was Q equals 3.367 L. H. i Where Q equals discharge in cubic feet per second, L equals length of crest in feet, and H equals head or depth of water on the crest in feet. The above is the formula used in general practice for the determination of the discharge over this type of weir and, provided certain conditions are maintained, has been determined to be within one per cent of accurate by many long series of complicated experiments. The conditions which must obtain to insure reasonable accuracy of measurement, and which, as near as possible, were observed throughout the investigation, are: (1) The weir proper should consist of a notch, trape- zoidal in shape and thin in section, preferably cut from a piece of metal such as 1 sixteen gauge galvanized iron. (2) The bottom edge of the notch should be a straight line either one, two, or three feet in length, or longer, de- pending upon the amount of water required, which should govern the size of the weir. The sides of the notch should slope outward at the rate of one horizontally to four ver- tically, thus a one foot Cippoletti weir should have a bot- tom or crest length of exactly one foot and a top width, with a depth of six inches, of fifteen inches, both sides of the weir sloping outward at the same angle. (3) All water to be measured should be passed through the notch or over the weir. The notch or weir must be set vertically Avith its crest or bottom in a horizontal position, and the entire plate or notch should be perpendicular to the axis of the stream. (4) The water should have a free fall over the weir, i. e.y the water below the weir should not back up so as to drown or submerge it. There should be enough clearance so that air can circulate freely under the issuing stream at all times. (5) The water should enter the weir slowly, being brought to a state of rest if possible before entering or passing over the weir. This is usually secured by digging a rather deep, wide pool above the weir or by building the weir box of large enough cross section to insure a slow "velocity of approach," which is very necessary if accurate measurement is to be obtained. (6) The depth of water flowing over the crest of the 70 REPORT OF STATE ENGINEER. weir should not be measured on the crest but from a point level with the crest and up-stream from it, a distance of about twice the length of the crest. This is necessary, as the water has a downward curve as the crest is approached, and the depth moist be measured from still water if the formula is to give accurate measurement. The best and most common method of setting a point from which to measure the water, and the one that was used throughout the investigation, is to set a heavy 2x4 or 4x4 peg or stake in the pool up-stream from the weir. This peg should be heavy enough so that it cannot be readily disturbed, and should be driven from one-half to an inch below the level of the weir crest. A heavy nail or spike should then be driven vertically into the top of the stake, the upper face of the spike being exactly levelled with the crest of the weir by means of a carpenter's or engineer's level, the weir having previously been established in the weir box both vertical and horizontal and at right angles to the axis of the stream entering the weir box. The head on the weirs was measured by the observers with small steel rules graduated to one-hundredth of a foot. During measurement the observer held his eye as close to the surface of the water in the pool as possible and extend- ed the thin rule down through the water to the head of the nail, the height of the water on the rule being noted, which gave the correct head on the weir. (7) The depth of water flowing over the crest should never be allowed to exceed one-half of the crest length, and it is preferable that it should not exceed one-third of the crest length. Where it is desired to measure so much water that it gives too great a depth on a one-foot weir, a two- foot weir or a three-foot weir, as the case may be, should be installed. Accurate measurement demands that there should never be less than one inch of water flowing over the crest. This is necessary in order to secure complete contraction of the issuing stream, which is very essential. Obstructions of any kind should not be permitted. The sides of the weir box or pool should never approach the sides of the weir. The distance between the edge of the issuing stream and the outer edge of the box for small weirs should always be at least twice as great as the depth of water flowing over the crest. It has been determined by experiment that the following conditions are necessary if a slow velocity of approach is to REPORT OF STATE ENGINEER. 71 be secured on weirs. These conditions are not ironclad, however, and may be varied slightly, the slow velocity of approach and an unobstructed free fall of the issuing stream being the things most of all desired. The cross sec- tion of the stream in the weir box or in the pool above the weir should be at least seven times as great as that of the stream which issues through and over the weir crest. The height of the crest above the bottom of the box or pool should be at least twice and preferably three times that of the depth of the water over the crest. In order to better illustrate the conditions that must ob- tain for accurate measurement and the conditions that Avere observed throughout the Duty of Water investigation, the following cut of an ideal weir and weir box are in- serted : '> i ,V/;. ''"<*l'l 'i, -4^/-*V^W.. \v //> v /, . ', ''/// ,,/'// i \ ' " K * ' "* f / I ti '" I/' // /' //// ;,^ix \ti',y !&,.. ;/;; iv^i^ "* >;^/ / y- tww./ l .>! l f-tjt'ijtl' l >;iv'i -.',' ;\ f m^h''A'';' ! ' \: ^Mf/J'Wfyj.ii, ^^^r/^^y^?^^^^!^ ^-^ J ' '\"W^^ &'** - ' " A \^%, tzf'^' , s, / :' // ''' , , ^\ N ^ZLrli&'tf'^tf'te' , f & w /^/y ^ ;,/. y < /> o/ 1 " ,. ' - \ ^ :< ^^&-^^ \\ ' \^ \^^S^^fk ^^'^/'y H ^/^t^ ' fe&^A 11 1 REPORT OP STATE ENGINEER. 73 The weir box shown in the above cut is no part of the weir proper and is necessary for the sole and only purpose of holding the weir in place and forcing all of the water to pass over it without leakage. Some writers insist on longer boxes or boxes of specific dimensiop, but these dimensions have been arrived at and are given in order to insure a suf- ficient size of cross section to insure free fall over the weir, complete contraction of the issuing stream, and a slow velocity of approach. The above canditions may be obtained, including a slow velocity of approach, if the fore- going instructions are carefully observed, and a compara- tively deep, wide pool is maintained in the ditch above the weir box. The following table has been compiled for the use of irrigation farmers and others, the depths on the crest be- ing given in inches and fractions of an inch rather than in hundredths of a foot in order that the irrigators may use the table in connection with the ordinary rules in com- mon use, such as school rulers, yard sticks, carpenter's rules, or squares instead of special rules graduated to hun- dredths of a foot, which are not commonly accessible. This table gives the discharge over the smaller sizes of weirs both in cubic feet per second and in Idaho miner's inches, of which there are fifty in a "second foot." 74 REPORT OF STATE ENGINEER. DISCHARGE OF CIPPOLETTI WKIRS IN IDAHO MINER'S INCHES AND SECOND FEET. Depth of water on crest inches One-foot weir Two-foot weir Three-foot weir Second feet .010 .029 .053 .081 .113 .149 .188 .229 .273 .320 .369 .421 .474 .531) .588 .648 .709 .773 .839 .906 .974 1.044 1.116 1.191 Miner's inches Second feet .020 .058 .106 .162 .226 .298 .376 .458 .546 .640 .,38 .812 .948 1.060 1.176 1.296 1.418 1.546 1.678 1.812 1.948 2.088 2.232 2.382 2.531 2.684 2.841 3. COO 3.162 3.327 3l%96 3.664 3.838 4.014 4.192 4.374 4.557 4.744 4.932 5J24 5.316 5.510 5,709 5.910 6.112 6.317 6.525 6.734 Miner's inches Second feet Miner's inches % J /a *4 1 o % \ Va % 3 g % 4 tt * % e^ | % 1 % 9 % J ) | * 0.5 1.6 2.7 4.1 5.7 7.5 9.4 U.5 13.7 16.0 18.5 21.1 23.7 26.5 29.4 32.4 35.5 38.7 42.0 45.3 48.7 52.2 55.8 59.6 1.0 2.y 5.3 8.1 11.3 14.9 18.8 22.9 27.3 32.0 36.9 42.1 47.4 53.0 58.8 64.8 70.9 77.3 83.9 90.6 97.4 104.4 111.6 119.1 126.6 134.2 142.1 150.0 158.1 166.4 174.8 183.2 191.9 200.7 209.6 218.7 227.9 237.2 246.6 256.2 265.8 275.5 285.5 295.5 305.6 315.9 326.3 336.7 .030 .087 .159 .243 .339 .447 .564 .687 .819 .960 1.107 1.263 1.422 1.590 1.764 1.944 2.127 2.319 2.517 2.718 2.922 3.132 3.348 3.573 3.796 4.026 4.261 4.500 4.743 4.990 5.244 5.496 5.757 6.021 6.288 6.561 6.835 7.116 7.398 7.686 7.974 8.265 8.563 8.865 9.168 9.475 9.787 10.101 1 1.5 4.4 8.0 12.2 17.0 22.4 28.2 34.4 41.0 48.0 55.4 63.2 71.1 79.5 88.2 97.2 106.4 116.0 125.9 135.9 146.1 156.6 167.4 178.7 189.8 201.3 213.1 225.0 237.1 249.5 262.2 274.8 287.9 301.1 314.4 328.0 341.8 355.8 369.9 384.3 398.7 413.3 428.2 443.2 458.4 473.9 489.4 505.0 . The above table gives the discharge of the smaller sizes of Cippoletti w^irs in cubic feet per second and in Idaho miner's inches, but is not of much use to the ordinary ir- rigator in determining the exact depth or quantity that he has applied to his land in acre feet. For the use of those who care to calculate the amounts that have been applied either as acre feet or as depths on the land, the fol- lowing table is included, it having been devised to facili- tate the enormous amount of computation in connection with the four seasons' Duty of Water Investigation. From it REPORT OF STATE ENGINEER. 75 may be obtained the number of acre feet or fraction of an acre foot per hour that will be discharged over the smaller sizes of Cippoletti weirs such as will be used in common practice. In illustration of its use it will be seen from the table that a depth of three inches or 0.25 feet over a one foot Cippoletei weir will discharge .0348 acre feet per hour, or .348 acre feet in ten hours, or 3.48 acre feet in one hundred hours, which would cover one acre 3.48 feet deep in 100 hours. DISCHARGE OF CIPPOI^ETTI WEIRS IN ACRE FEET PER HOUR. u Acre feet V* ' l| Acre feet Ui a> -g Acre || Acre v< > *2^ feet in one feet in one S-, ' in one hour M-i -i in one hour oc 5 bj 3 < a & Seasonof 1910 Blackfoot 14 25 3 5 1 10.46 12.71 12.22 10.54 4.66 4.10 5.13 3.51 0.67 1.10 0.82 1.05 0.77 0.81 0.06 0.33 0.73 1.59 0.86 1.03 1.15 1.67 0.95 0.15 0.43 1.35 3.34 .92 .96 .96 .94 .68 .38 0.95 0.62 0.47 0.89 iO.35 0.15 ' "6.'53 0.78 1.14 0.55 0.84 0.32 0.80 0.75 0.43 0.52 2.57 1.97 1.13 1.77 2.91 2.29 1.75 1.74 2.00 1.94 0.43 2.05 1.33 1.36 0.63 0.57 0.58 1.58 0.15 1.79 2.39 1.36 1.25 0.75 0.10 0.30 0.25 0.03 0.08 0.06 0.14 0.01 0.06 2.55 2.34 1.44 1.06 1.53 2.67 2.76 0.83 1.95 0.86 0.90 1.77 0.67 0.89 0.46 0.86 1.64 2.49 0.91 2.40 2.99 3.01 4.32 2.54 0.21 T 0.28 T 0.24 0.27 o.n 0.18 0.12 0.05 0.18 0.23 0.04 0.30 0.84 0.05 T 1.27 0.18 1.22 0.33 1.60 0.48 0.04 2.01 2.29 0.73 .65 .86 .85 .29 .50 T T ? T j 0.07 0.04 0.07 0.08 0.21 T ' 2.28 0.16 T ' 0.03 0.13 0.08 0.13 0.08 0.84 1.17 0.17 0.47 0.50 2.23 3.04 48 74 Boise Buhl Caldwell 0.89 0.44 1.33 1.30 0.54 0.95 0.04 T 0.12 T 0.03 10.67 0.30 0.10 T 0.77 0.30 0.53 0.18 0.44 0.30 0.31 0.65 0.05 0.05 0.49 0.88 0.65 "2.'09 2.81 1.85 3.27 2.36 1.49 2.38 6.80 5.35 3.95 S.98 6.18 6.95 5.80 3.19 5.30 8.25 3.81 7.74 3.47 8.51 3.71 3.16 5.86 7.16 2.39 7.35 8.55 7.86 "i.'ss 80 '"81 39 51 54 166 103 110 124 144 115 124 76 134 201 76 18, 107 137 90 83 14H 13fi 7? 109 13* ..^. 167 Gooding Hailey 8 15 3 5 26 4 6 2 9 16 18 6 3 27 5 7 3 17 7 4 28 7 4 2 18 19 8 17.15 14.44 15.06 12.90 12.71 11.15 10.31 9.40 16.27 14.00 9.58 12.10 13.86 12.71 10.90 10.05 10.82 14.23 11.98 13.76 12.71 11.25 11.14 12.97 14.35 9.99 'ii.'is 4.04 6.00 2.91 4.40 4.10 5.17 3.59 3.20 4.30 6.06 4.68 4.19 3.96 4.10 4.99 4.13 3.24 6.19 4.13 3.82 4.10 5.25 3.04 6.74 6.32 5.04 4.54 Idaho Falls Twin Falls Season of 1911 Boise Buhl Caldwell Gooding Hailey Idaho Falls Oakley Twin Falls Wendell Season of 1912 Boise Buhl Caldwell Gooding Idaho Falls Twin Falls Wendell Season of 1913 Boise Buhl Gooding Hollister Idaho Falls Oakley Rogerson Twin Falls 84 REPORT OF STATE ENGINEER. Method of Interpreting Results. The correct and proper analysis of the results that have been secured has been the most difficult part of the en- tire investigation. There are so many factors other than mere amount of water application that might influence the yields that have been secured from the experimental tracts that the proper interpretation of the results has indeed been a difficult problem. It has been plain that under normal conditions the tract producing the best yield has had the best application of water for the soil and crop in question. In some cases, however, the largest yield has exceeded the yield of one of the other two tracts by less than 5 per cent, yet the amount of water applied might have exceeded that applied to the second tract by as much as 100 per cent. In such cases it has been plain if economy of time and water are to be considered that the tract making the smaller yield was handled more economically. The investigation as a whole has made it plain that a single experiment is not dependable, because of the in- sidious 1 variations that sometimes unavoidably creep in. There have sometimes been great variations in the yields produced by the same amount of water on the same crop upon adjoining farms during the same season. It became evident beyond contradiction early in the investigation that the results secured from a large number of tracts con- sisting of a considerable area were the only data that would be found dependable; also that an average of the data secured during as many years as possible was the most dependable for in no other way could the peculiarities of the individual tracts or the seasonal variations in the climate be neutralized. It was found early in the investigation that the various crops naturally formed themselves into two groups: (1) those requiring the least water; and (2) those requiring the most water. The grains, both spring and winter, potatoes, and clean cultivated orchards were found to lie in group No. 1, while alfalfa, the clovers and pasture were found to lie in group No. 2, the crops in the second group requiring nearly twice as much water as the crops in group No. 1. The following tables have been compiled and give in a condensed form a brief resume of the experiments that have been conducted. The crops are grouped in the tables according to their water requirements into groups No. 1 and No. 2. It is to be regretted that the enforced KEPOBT OF STATE ENGINEER. 85 brevity of this report will not permit of even a brief de- tailed description of each experiment, the space allotted to each experiment in the tables which follow being the only detailed description of each experiment that can be in- cluded. These tables show, (1) the kind of crop, (2) the altitude, (3) a brief description of the class of soil, (4) the area of each tract experimented upon, (5) the precipi- tation recorded at the nearest Weather Bureau Station, (6) the date of the first irrigation during the season, (7) the length of the irrigation season in days, (8) the number of irrigations that were applied during the season, (9) the total depth of irrigation water that was applied and retained upon the tract in question, all waste water hav- ing been deducted, unless otherwise specified, and (10) the yields that were secured per acre. For convenience the results from the three or more plots on each farm are grouped together, the experiments on the different farms being separated slightly in the tables. The readers are requested to bear in mind that the "total depth ap- plied" includes only the irrigation water that was retained upon the tract in question, the rainfall during the season being given in another column. 86 REPORT OF STATE ENGINEER. Table Showing- Effects of Using- Different Amounts of Water on Grains. Alfalfa, Etc., in Idaho, During the Seasons of 1910-11-12-13. Kind of crop Grain-1910 lOats 2 Oats 3 Oats . Wheat 5 Wheat (> Wheat Wheat 8 Wheat 9 Wheat 10|Oats Wheat Wheat 13 Wheat 14|Wheat 15|Wheat 16 Wheat 17 (Oats ... !8|Oats ... !9|Oats ... 20jOats ... 2l(Oats ... 22|Oats ... 23 Wheat 24 Wheat 25 Wheat Oats Oats 28 Oats 29 Wheat 30 Wheat ., 31 Wheat 32|Oats 33|Oats 34 Oats 35 Wheat... 36 Wheat 371 Wheat , 38|Oats 39|0ats 40!Oats 41 1 Wheat.. 42! Wheat. . 431 Wheat.. 44 1 Wheat., 45| Wheat.. 50 Wheat.. 51! Wheat., I 521 Wheat., 531 Wheat., 54 1 Wheat. Class of soil 3968 Slightly Sandy Loam. 3968 Slightly Sandy Loam. 3968 Slightly Sandy Loam. 3800 Medium Clay Loam ^800|Medium Clay Loam.... :5800|Medium Clay Loam 4949 1 Very Gravelly... 4949| Very Gravelly Gravelly 4949 1 Very 1949; Very 4949 Gravelly. Very Gravelly 4949 Very Gravelly -1949 Very Gravelly 4949 Gravelly Clay , 1949 Gravelly Clay 4949 Gravelly Clay 1699 Very Gravelly 4699 Very Gravelly 4699|Very Gravelly 47 421 Impervious Clay Loam. 4742! Impervious Clay Loam. 4742| Impervious Clay Loam. 4497 Very Sandy. 4497 Very Sandy. 4497 1 Very Sandy. 2482 Impervious Clay Loam. 2482 Impervious Clay Loam. 2482 Impervious Clay Loam. 2607 Uniform Clay Loam... 2607 Uniform Clay Loam . . . 2607|Uniform Clay Loam... I 2460| Coarse Sandy Loam. 2460 Coarse Sandy Loam. 2460 Coarse Sandy Loam. 3800 1 Uniform Clay Loam. 3800IUniform Clay Loam. 3800'Uniform Clay Loam. 24821 Impervious Clay Loam 24821 Impervious Clay Loam 2482!Impervious Clay Loam 3572 1 Medium 3572 1 Medium 3572|Medium 3572 Medium 35 riMcUum, ?572 1 Medium ,'572 1 Medium I 3572 (Medium 3572 1 Medium 3572' Medium Clay Loam. Clay Loam. Clay Loam. Clay T.'Oam. Clay Loan- Clay Loam. Clay Loam . Clay Loam . Clay Loam . Clay Loam. 2.90| 5-27 3.041 5-21 3.04| 5-20 3.04! 5-19 605.1 Ibs 1227.3 Ibs 1238.6 Ibs RKPORT OF STATE ENGINEER. 87 Table Showing Effects of Using- Different Amounts of Water on Grains, Alfalfa, Etc., in Idaho, During- the Seasons of 1910-11-12-13. Continued. Kind of crop Grain 1910 Continued 1 55 1 Wheat jtijWheat o7| Wheat uSi Wheat 591 Wheat uO|Wheat 61| Wheat 62| Wheat t>3. Wheat 64 (Wheat 05 Wheat 66|Barley t>7|Barley tiSI Barley 69|Oats iGOats 71 Oats 72| Wheat 73 Wheat 74 Wheat Wheat.. 76 Wheat.., 77 78 Potatoes 79 Potatoes 80 Potatoes Wheat. 81 Oats 82 Oats Oats Alfalfa, Etc. 1910 1 Alfalfa... 2 Alfalfa 3 Alfalfa. 4 Alfalfa. 5 Alfalfa. 6 Red Clover. 7 Red Clover, si Red Clover. 91 Alfalfa... 101 Alfalfa 11! Alfalfa 121 Alfalfa 13| Alfalfa 14| Alfalfa 15| Alfalfa... 16! Alfalfa 17! Alfalfa I 18| Alfalfa 3572 1 Medium 3572 i Medium 3572 j Medium 3572 1 Medium 3572|Medium 3572 1 Medium 3572 Medium 3572|Medium 2|Medium 3572 1 Medium J572J Medium 3572|Medium 3572 1 Medium 3572jMedium 3572 1 Medium 55721 Medium 5572 1 Medium I 5572 1 Medium 5572 1 Medium 35721 Medium 3572|Medium ;572|Medium ]572|Medium 3572| Medium 5572 1 Medium 35,2|Medium 3572 3572 3572 Medium I 44971 Very 4497|Very 4497! Very 2367|Impervious Clay Loam lass of soil 1 Area acres SI it Date of first irrigation Ir. season days rt "o 'Total depth irri- gation water L- applied feet 1 Clay Loam . .086 1.85 5-20 43 4 .945 143 Clay Loam..... .089 1.85 5-20 54 5 1.100 193 Clay Loam...., .074 1.85 5-20 Gl 6 1.601 20C Clay Loam .089 1.85 5-21 GO 9 2.355 21C Clay Loam .176 1.85 .000 52 Clay Loam .088 1.85 *5-20 'a 2 .434 122 Clay Loam .089 1.85 5-20 43 9 .594 135 Clay Loam .091 1.85 5-20 43 4 .907 182 Clay Loam .088 1.85 5-20 54 5 1.091 210 Clay Loam .093 1.85 5-21 GO 1.786 225 Clay Loam .074 1.85 5-21 GO y 3.010 263 Clay Loam .962 1.85 5-17 32 3 1.032 15C Clay Loam .963 1.85 5-17 58 4 1.312 17S Clay Loam .968 1.85 5-18 G8 5 1.879 202 Clay Loam .959 1.85 5-24 23 2 .560 144 Clay Loam .957 1.85 5-25 41 3 1.097 184 Clay Loam .962 1.85 5-23 51 4 1.450 204 Clay Loam 563 1.85 5-26 22 2 .780 117 Clay Loam .591 1.85 5-26 4U 3 1.269 153 Clay Loam .769 1.85 5-26 GO 4 1.841 158 Clay Loam .959 1.85 5-9 23 2 .808 137 Clay Loam .964 1.85 5-9 42 3 1.101 121 Clay Loam .968 1.85 5-9 51 4 1.327 174 Clay Loam .641 1.85 5-13 68 3 .876 630 Clay Loam .652 1.85 5-13 88 5 1.496 1193 Clay Loam .636 1.85 5-13 97 6 2.046 1293 Clay Loam 5.70 1.85 5-12 64 3 1.401 4 Clay Loam 4.48 1.85 5-17 60 4 1.766 5 Clay Loam 1.98 1.85 5-19 59 4 2.486 7 Clay Loam ; .983 1.85 5-8 88 G 4.49 Clay Loam \ 5.75 1.85 5-7 43 2 1.306 Clay Loam 3.72 1.85 5-9 79 8 1.872 Clay Loam 3.56 1.85 5-10 78 3 2.104 ravelly 10.65 2.36 5-27 88 g 11.20 ravelly 3.31 2.36 5-6 113 7 6.92 ravellv 4.32 2.36J K-7 L17 9 8.40 ravelly 3.98 2.36 5-4 L14|10 12.98 ravellv 2.33 2.36 5-3 101 4 6.352 ravelly 6.77 2 36 5-2 105 6 6 925 ravelly 2.51 2.36 4-27 110 7 9.401 Clay Loam.... 3.20 2.36 5-6 104 4 1.409 Clav Loam 3.16 2.36 5-6 102 6 1.953 Clay Loam.... 3.37 2.36 5-6 103 6 2.221 indv 3.38 2 23 5-27 86 n 7 KM indv 4.15 2.23 5-27 50 5| 2.649 vndv. .. 4.29 2.23 5-27 59 71 4.825 2.81 | 2.81| 3-29|144( 8( 1.895 Yield per acre Ibs Ibs Ibs Ibs Ibs Ibs Ibs Ibs Ibs Ibs Ibs 1509.4 Ibs Ibs 2026.9 Ibs L2 Ibs 1.5 Ibs f.8. Ibs 1.4 Ibs 1.8 Ibs L.3 Ibs 1.4 Ibs ..6 Ibs !.8 Ibs !.6 Ibs 1.5 Ibs !.3 Ibs 43.3 bu 54.6 bu 73.7 bu 8.7 tons 3.30 ton? 3.56 tons 4.74 tons 4.2 tons 3.78 tons 4.85 tons 4.60 tons 3.78 tons 3.65 tons 5.20 tons 5.04 tons 3.41 tons 5.72 tons 4.44 tons 4.28 tons 4.57 tons 4.00 tons 88 REPORT OP STATE ENGINEER. Table Showing Effects of Using Different Amounts of Water on Grains, Alfalfa, Etc., in Idaho, During the Seasons of 1910-11-12-13. Continued. Number Kind of crop Altitude Class of soil Area acres Is Bd s& 19 20 21 22 23 24 25 26 27 28 Alfalfa, Etc. 1910- Cont. Alfalfa 2367 2367 2482 21S2 2482 '607 [Impervious Clay Loam [Impervious Clay Loam Impervious Clay Loam Impervious Clay Loam Impervious Clay Loam Uniform Clay Loam Very Gravelly Very Gravelly 3.69 2.84 6.32 6.23 6.21 5.08 158.4 15.2 51.0 2.81 2.81 3.00 3.00 3.00 2.80 3.27 3.27 1.85 3-27 3-28 5-7 5-5 5-5 4-28 143 114 115 120 99 in'j 120 m 140 8 'J 7 7 6 .. 2.848 3.66 tons 3.457 4.37 tons 1.434 2.85 tons 2.112 4.93 tons 2.251 4.35 tons 2.821 5.15 tons 21.13 3 to 3.5 tons 16.00 3 to 4 tons 4.80 4 tons 4.06 4 tons 4.00 4 tons 2.34 6.86 tons 4.05 7.04 tons 4.72 7.96 tons .453 29!5 bu 1.144 46.9 bu 1.889 50.8 bu .864 30.6 bu 1.623 33.8 bu 2.153 38.0 bu .635 63.2 bu 1.123 53.4 bu 1.808 64.0 bu 1.161 64.3 bu 1.414 51.9 bu 1.442 65.3 bu .302 56.6 bu 1.167 63.2 bu 2.266 68.9 bu .268 * .729 11.6 bu .656 23.3 bu .888 26.0 bu 1.047 35.0 bu .613 112.8 bu .955 108.1 bu 1.062 128.1 bu .641 76.5 bu 1.316 73.5 bu 1.654 I 72.4 bu 1.377 20.9 bu 5.342 | 30.0 bu Alfalfa Alfalfa . . . Alfalfa Alfalfa Alfalfa Alfalfa .... 5820 5330 3572 3572 3572 3SOO 3sOO 3800 3968 3968 3968 3800 3800 3800 3750 3750 3750 3750 3750 3750 3825 3825 3825 3825 3700 3700 3700 3700 3700 3700 3700 4100 4100 4100 4949 4949 No Alfalfa Alfalfa Alfalfa Alfalfa and Wheat Alfalfa Alfalfa Clay Loam Uniform Clay Loam Uniform Clay Loam Medium Clay Loam Medium Clay Loam Medium Clay Loam Uniform Sandy Loam... Uniform Sandy L825|Medium Clay Loam 3700|Very Sandy Loam 3700 Very Sandy Loam 4100lDeep Clay Loam 4.17 4.22 4.96 4.37 4.19 4.78 2.65 1.80 9.98 10.65 5.45 5.28 5.73 3.31 4.32 3.98 3.37 3.48 3.37 4.94 4.21 9.39 5.43 5.46 4.53 156.3 40.49 2.37 6.54 8.27 4.58 5.68 7.72 4.16 1.83 3.86 3.23 6.91 6.05 6.09 4.85 4.41 3.19 3.19 3.19 3.19 3.19 3.19 5.30 5.30 5.80 6.95 6.95 6.95 6.95 6.95 6.95 6.95 6.80 6.80 6.80 6.80 6.80 6.80 6.80 6.80 6.80 6.18 6.18 3.71 3.71 3.71 3.71 3.71 3.71 3.71 3.71 3.71 3.71 3.81 3.81 3.81 3.81 3.81 6-4 5-6 5-8 5-17 5-13 5-14 5-10 5-4 5-20 5-19 5-22 5-23 5-22 5-20 5-20 5-19 6-3 6-3 6-3 4-26 4-25 4-25 4-21 4-26 4-25 6-11 6-15 6-21 6-24 6-18 8-1 6-7 6-9 6-6 6-5 6-3 6-1 6-26 6-18 6-23 6-3 6-4 80 135 135 105 112 100 119 125 lOb 77 1)4 94 88 ID: 10! 10J, 10"> 10o 111 142 141 122 119 11! 67 t;r '' 22 ffi 51 39 53 57 '37 34 39 00 2 4 5 3 4 5 6 6 1 8 -1 7 G 5 7 g 8 8 (] 11 12 7 8 c 1 ] 2 1 2 3 4 2 3 -f i| ! 3 1.286 3.194 3.981 1.309 2.767 3.211 1.894 2.611 .993 11.532 5.402 6.400 7.224 5.246 6.611 14.721 1.535 2.912 4.114 2.136 3.511 3.814 3.257 4.437 6.040 10.91 8.562 .735 .871 1.158 .143 .927 1.436 1.598 .487 1.427 1.748 .276 .791 ! 1.214 M 1.655 6.1 tons 6.4 tons 5.76 tons 4.73 tons 5.44 tons 4.97 tons 1.50 tons 2.74 tons 3.1 tons 4.54 tons 1.99 tons 3.42 tons 3.27 tons 2.69 tons 3.25 tons 2.91 tons 0.1 tons 0.1 tons 0.89 tons 2.11 tons 3.93 tons 4.39 tons 4.63 tons 4.57 tons 3.84 tons 3.00 tons 3.00 tons i 67.5 bu 72.1 bu 82.9 bu * 31.16 bu 37.65 bu 28.60 bu 10.92 bu 25.90 bu 24.76 bu 15.92 bu 18.02 bu 24.11 bu 39.59 bu 43.76 bu Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa Alfalfa 494: \ r erv Gravelly 4949) Very Gravelly 4949| Very Gravelly 4949 Very Gravelly Alfalfa Clover 4949 Very Gravelly Clover Clover Alfalfa Alfalfa Alfalfa........ Alfalfa Alfalfa Alfalfa Timothy & Clover Timothy & Clover 4949 Very Gravelly 4949 Very Gravelly 2607|Clav Loam 2607|Clay Loam 2607 Clay Loam 2607 1 Impervious Clay Loam. 2607 Impervious Clay Loam. 2607 ! Impervious Clay Loam. 2547| Dark Sandv Loam 2547 j Dark Sandy Loam 25471 Dark Sandy Loam . . Timothy & Clover 5820|Very Gravelly 5330 'Very Gravelly Alfalfa and Grain Alfalfa Grain 1912 Wheat Wheat 3800 Medium Clay Loam 38001 Medium Clay Loam.... 3800|Medium Clay Loam 3825|Medium Clay Loam 4000 Shallow Gravelly Clay.. 4000|Shallow Gravelly Clay.. 40001 Shallow Gravelly Clay.. 4000 Shallow Clay Loam 4000!Shallow Clay Loam.... 4000IShallow Clay Loam 3800 Shallow Clav Loam 38001 Shallow Clay Loam.... 3800|Shallow Clay Loam 3750|Deep Clay Loam 37501 Deen Clav Loam... Wheat Orchard Wheat Wheat Wheat Oats |Oats... lOats Wheat Wheat Wheat Wheat Wheat... * Only five years old, very small yield, not .measured. 92 REPORT OF STATE ENGINEER. Table Showing Effects of Using Different Amounts of Water on Grains., Alfalfa, Etc., in Idaho, During the Seasons of 1910-11-12-13. Continued. Number Kind of crop Class of soil ft < Area acres Is 3 a *& %$ *& ,5 3 Impervious Clay Loam. ^i2\ Medium S5'<2 Medium $572| Medium a?2i Medium 55<2l Medium Class of soil Area acres Clay Loam. Clay Loam. Clay Loam. Clay Loam. Clay Loam. Clay Loam. SOOi Meaium Clay Loam. ;5800|Medium Clay Loam. 5800!Medium Clay Loam. ! :,S90| Shallow Clay Loam. JSOOjShallow Clay Loam. 38001 Shallow Clay Loam. ! :*"<50|Deep Clay Loam 3750|Deep Clay Loam 3750|Deep Clay Loam H800|Shallow Clay Loam 2607|Clay Loam 2607|Clay Loam 2607IClay Loam '949| Porous Gravelly. 4949! Porous Gravelly. 4949 1 Porous Gravelly. 4949|Porous Gravelly. 4949|Porous Gravelly. 4949| Porous Gravelly. I 4550 1 Clay Loam. 4550|Clay Loam. 4550|Clay Loam. 4550iClay 4550|Clay 4550 1 Clay ! 4550 1 Clay 4550 1 Clay 4550!Clay 4550|Clay 45501 Clay 4550! Clay 4850| Deep Uniform Clay. 4850|Deep Loam Clay.... 4850! Deep Loam Clay Loam. Loam. Loam. Loam. Loam. Loam. Loam . Loam . Loam. 4700|Deep Unif'm Clay L'm. 4700|Deep TTnif'm Clay L'm. 4700|Deep Unif'm Clay L'm. Oatg 4700|Deep TTnif'm Clay L'm. Oats 4700J Deep Unif'm Clay L'm. Oatg 4700|Deep Unif'm Clay L'm. d .372 .585 .372 .569 .369 .580 6.02 7.49 7.71 4.24 3.38 3.75 4.74 4.82 5.28 14.28 4.77 3.62 6.10 4.36 4.94 4.75 3.68 2.65 2.13 2.70 3.45 3.44 5.08 5.06 5.07 3.01 4.17 3.03 3.53 6.06 4.45 7.52 5.12 6.60 6.00 5.16 3.07 4.73 4.80 4.90 B 3.47 3.47 3.47 3.471 3.471 5-14| 88 3.47| 5-27 5-1 5-1 5-14 Total depth ir gation water applied feet Yield per acre I 3.711 3.711 3.71| 3.81| 3.81| 3.81| 3.811 3.811 3.811 ! 3.81| I 8.25! 8.25! 8.25! 8.51! 8.51| 8.511 5-15| 86 I I I 5-22| 95| 3| 5-24| 90 | 3| 5-16|123| 61 I I I 5-14|107| 7 5-14 1 107 1 6 5-1311071 9 I ! I 5-31! 97| 3| 5-24! 92| 4| 5-24|100| 4| I I ! 5-271 98! 4! I I I 5-171101! 6! 5-16| 98| 6| 5-191105! 7! I I I 5-31! 75! 5| 6-21| 55| 3| .615 1.308 2.059 2.533 2.931 4.003 1.708 2.070 3.381 2.339 2.513 3.153 1.064 1.589 1.799 2.413 1.870 2.961 2.887 5695.0 8003.0 10828.0 11317.0 12506.0 12612.0 1.983 2.027| 6-1 I 75! 6! 2.582 8.511 8.51! 8.51! I I | 7.35! 7.35! 7.35) I 7.35! 7.35! 7.35| I 7.351 7.351 7.35! I 7.351 7.351 7.35! I 7.35! 7.35! 7.351 I 7.35! 7.35! 7.35! 7.35! 7.35! 7.35| ! !' 6-4 | 71 6-5 ! 71 6-4 | 71 I I I I ! 5-31! 90! 3! 5-31! 871 41 5-301 89| 6! I I I 7-2 |... 1! 6-30! 29! 2! 6-28! 29| 21 I I I 6-22! 231 21 6.24! 38! 3! 6-6 ! 58! 4! ! I ! 5-1011091 5| 5-141 99! 4! 5-101105! 5! ! I ! 5-29! 63! 2| 5-7 1107! 3! 5-4 1109! 4| 6-30! 391 3! 6-27! 35' 3| 6-25! 43! 31 I I I 6-8 ! 58! 3! 6-6 I 471 3! 6-5 | 49! 3| Ibs Ibs IDS Ibs Ibs Ibs 3.047 3.307 6.721 I I I I 1.28501 1.9607! 2.6876! I .3554! .8939! 1.3291! I .9954! 1.6230! 2.3346! I 2.34451 2.6808! 3.2882! i 1.41901 2. 4645 ' 3.7354' | .7579! 1.3089! 2.2844! 1 .7833! 1.2642! 1.57221 5.94 tons 5.84 tons 5.70 tons 6.44 tons 5.90 tons 7.04 tons 4.67 tons 4.42 tons 4.80 tons 6.00 tons 4.31 tons 4.11 tons 3.89 tons 2.52 tons 1.48 tons 1.58 tons 1.82 tons 2.00 tons 2.50 tons 3.06 tons 2.51 tons 3.03 tons 33.85 bu 36.95 bu 33.82 bu 24.24 bu 25.77 bu 16.99 bu 17.13 bu 18.72 bn 20.45 bu 3.83 tons 4.00 tons 3.68 tons 24.66 bu 23.83 bu 31.59 bu 41.22 bu 41.45 bu 41.22 bu 94 REPORT OF STATE ENGINEER Table Showing Effects of Using Different Amounts of Water on Grains, Alfalfa, Etc., in Idaho, During the Seasons of 1910-11-12-13. Continued. Kind of crop J5 g 3 55 Class of soil s < Area acree Is 3d *& 8S *%. G4 Date of first irrigation Ir. season days j. p. rt =f u o Y+ Total depth irri- gation water applied feet Yield per acre Grains, Etc. 1913-Cont. 22jAlfalfa 4300|Deep Clav Loam 3 82 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.35 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.86 7.58 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 2.39 5-26 5-7 5-4 6-27 6-24 6-21 6-7 6-4 6-5 6-28 6-27 6-26 5-31 5-11 5-28 6-24 6-25 8-8 7-12 7-16 7-18 5-26 5-27 5-28 5-20 5-18 5-22 7-17 'e-3' 6-3 6-4 6-4 6-4 6-5 '6-S' 6-4 6-4 6-4 6-4 6-5 74 95 112 13 17 1? 25 40 69 17 IS is 70 97 72 17 37 34 33 .... '.'.*. 62 68 . 4 '35 34 48 48 53 * 34 48 48 53 ;; 4 6 > 2 2 2 3 3 2 1 3 4 4 1 1 2 2 2 2 1 1 1 2 t 3 \ \ 4 ! i 2 3 4 I"? 2 3 4 I 1 1 1.33271 3.94 tons 2.3552| 6.11 tons 3.5394! 6.10 tons D .47371 12.29 bu .88901 17.20 bu .92531 3.72 bu .65531 33.17 bu 1.39491 35.32 bu 2.18561 32.25 bu .70801 32.28 bu 1.00161 51.57 bu 1.2413! 46.80 bu .65141 34.42 bu 1.28351 44.88 bu 1.6017 49.33 bu .49301 39.7 bu .7139! 35.7 bu r 1.64321 15.72 tons 1 1.2930! 33.3 bu 1.7217! 36.5 bu 2.91091 16.6 bu 1.0440! 1.76 tons 1.5148! 2.6 tons 1.87781 2.84 tons r 1.85711 3.9 tons 1.7079! 4.1 tons 1.93751 3.89 tons .33941300 boxes .00 0.00 Ibs .29891 1030.93 Ibs .5147! 1558.58 Ibs .5412! 1661.60 Ibs .97761 1703.88 Ibs 1.1816! 1551.31 Ibs 1.8633! 2571.43 Ibs .00 1 0.00 Ibs .26441 1109.42 Ibs .4749! 1839.30 Ibs .6913! 2273.27 Ibs 1.1846! 1879.19 Ibs 1.2551! 1888.89 Ibs 2.1977! 3632.81 Ibs .00 0.00 Ibs .2576 1339.60 Ibs .4997 1922.60 Ibs .6903! 1377.91 Ibs .9300! 1321.32 Ibs 1.0969! 2531.65 Ibs 1.8359! 3542.48 Ibs 23| Alfalfa 24|Alfalfa 4300|Deep Clay Loam 4300|Deep Clay Loam 4850|Clav Loam 3.61 5.77 4.96 4.36 4.83 3.92 4.19 4.34 3.19 3.18 3.43 4.11 6.25 2.27 7.05 2.38 7.83 4.35 4.57 3.91 3.58 2.69 3.70 3.12 2.82 4.05 4.58 .190 .0873 .0956 .0987 .0851 .0838 .0945 .1925 .0987 .1033 .0838 .0894 .0945 .1024 .1949 .0851 .0801 .0987 .0999 .0869 .0765 25| Wheat 26|Wheat iSSftiniav Loam... 27 Wheat . -IS^Iflnv T.nnm 28|Wheat 29| Wheat 30|Wheat 4300iMedium Clay Loam 4300'Medium Clay Loam 4ouO'Medium Clay Loam 4300! Medium Clay Loam 4300| Medium Clay Loam 4300iMedium Clay Loam 4300 Medium Clay Loam.... 4300! Medium Clav Loam 4300[Medium Clay Loam.... 45 <0 Deep Unif'm Clay Loa' 45/0 1 Deep Unif'm Clay Loa' 4570!Uniform Clay Loam 45701 Deep Uniform Clay 4570!Deep Uniform Clav 4570'Deep Uniform Clay 4700|Deep Uniform Clay 4700|Deep Uniform Clay 4700IDeep Uniform Clay 4570|Deep Uniform Clay 4570|Deep Uniform Clay 4570IDeep Uniform Clay 3825 Medium Clay Loam..... 3572| Uniform Clay Loam . . . 35721 Uniform Clay Loam... 3572 Uniform Clay Loam... 3572! Uniform Clay Loam... 35721 Uniform Clay Loam... 3572|Uniform Clay Loam... 3572|Uniform Clay Loam... 3572IUniform Clay Loam... 3572|Uniform Clay Loam... 3572 (Uniform Clay Loam... 3572 Uniform Clay Loam... 3572|Uniform Clav Loam... 3572 Uniform Clay Loam... 3572 Uniform Clay Loam... 35721 Uniform Clay Loam... 3572!Uniform Clay Loam... 35721 Uniform Clay Loam... 3572|Uniform Clav Loam... 3572IUniform Clay Loam... 3572|Uniform Clay Loam... 3572|Unif orm Clay Loam . . . 31 Wheat 32| Wheat SS'Wheat 34 1 Oats . 35 1 Oats 36|0ats 37 Wheat 38lOats ! 39ISugar Beets. 40| Oats 4t|Oats 42IOats 43! Alfalfa... 44!Alfalfa 45! Alfalfa 4HI Alfalfa 471 Alfalfa 48! Alfalfa 49iQrchard 501 Wheat 51!Wheat . 52IWheat 531 Wheat 541 Wheat 551 Wheat StilWheat | 57| Wheat 581 Wheat < SfllWheat . . 60! Wheat .. 2| Wheat f,3| Wheat 64! Wheat , 65 1 Wheat 661 Wheat... 6-3 6-4 6-4 6-4 6-4 6-5 'si 34 48 48 53 67'Wheat GSlWheat 69! Wheat 70>Wheat 71|Wheat * REPORT OF STATE ENGINEER. 95 Table Showing Effects of Using- Different Amounts of Water on Grains, Alfalfa, Etc., in Idaho, During the Seasons of 1910-11-12-13. Continued. o* 5 ge IB n 'C 3d n f i III Yield hi Kind of crop o i Class of soil rea "W 3 S* ^ H 8 acres *2 S.I 1 "r o aj per acre 3 < 1 i S< a- C o c< a bcrt Grains, Etc. 1913- Cont. 72|Barley 3572|Uniform Clay Loam., i .6541 3572|Uniform Clay Loam 72 3572 Uniform Clay Loam.. Uniform Clay Loam.. Uniform Clay Loam.. .4325 .5271 .4731 2.39 2.39 2.39 5-22 5-21 5-10 86 NT <>7 3 1 5 1.1763110601.16 Ibs 1.81941 9685.07 Ibs 1.8194110410.06 Ibs 871 Alfalfa 3572] Uniform Clay Loam.. .5032 2.39 5-9 98| 7 1.9811 11705.09 Ibs 88| Alfalfa 3572!Uniform Clay Loam.. .4798 2.39 5-9 |109|10 3.0548113989.16 Ibs 89|Alfalfa 3572iUniform Clay Loam.. .537212.39 5-8 11181131 3.3388115022.34 Ibs The preceding tables show the major part of the crop tests that were included in the four seasons' Duty of Water Investigation. These tables give a brief resume of the results that were secured from 415 plots consisting of a total area of 1,842.5 acres devoted to the staple crops com- monly grown in South Idaho. The majority of the experi- ments was conducted with alfalfa and the grains, but all of the staple crops were represented. The four year's in- vestigation, from 1910 to 1913 inclusive, with its broad scope has thrown much new light upon -many important irrigation problems. Tt has proven that many old theories have an utter lack of foundation, has established as facts many other theories and has laid the foundation for many new ones. The chief facts that have been brought out and emphasized by the investigation will be briefly discussed later in the report. The investigation in general has shown that individual experiments cannot be depended upon for conclusions for the reason that the results of crop tests are often affected by external or unknown causes and that only the general average of a large number of results secured under approximately the same conditions should 96 REPORT OF STATE ENGINEER. be used. The experiments included in this investigation, however, have covered four seasons, some of which have been wet and others dry, hundreds of different tracts of different classes of soil planted to different crops have been included, and there is every reason to believe that a general average of such a large number of results secured during these four seasons will be found to be very reliable. It was found early in the investigation that there was a great variation in the water requirements of the various soils and crops. The soils and crops, however, so far as water requirements are concerned, have seemed to auto matically resolve themselves into two classes each, (1) those requiring the least water, and (2) those requiring the most water. The crops belonging to the first class, those requiring the least water, are spring and winter grains, potatoes, and clean cultivated orchards. Those belonging to the second class are alfalfa and other hay and pasture grasses. The soils that require the least water are the medium or clay and silt loam soils of a reasonable depth. This class includes adobe, lava ash, clay loam, and fine sandy soils, or any soil of & reasonable depth that isjiot porous. The soils requiring the most water are the porous soils, such as the coarse, sandy and gravelly soils. For the purpose of illustration, discussion and com- parison, the soils and crops will hereafter be tabulated and discussed in this report under the tAvo above-men- tioned classes. The average irrigated soil of Idaho, and of most other western states, falls in the medium or first- mentioned class, the percentage of extremely porous irri- gated soils being quite low. The tables and discussions in regard to the medium soils will therefore >be of mor^ use and interest than those dealing with the porous soils. The following tables have been compiled from results secured throughout the investigation with the medium or less porous type of soil. This table is made up ft) bv showing Hie average results secured from all of the alfalfa plots included in the investigation that were grown on medium soil, and (2} by selecting the plot which made the maximum yield from each 15-aere experimental tract, irrespective of the amount of water applied, and forming a general average of the results secured from all of them, some 26 in number. The same method of procedure has been followed with the grains. REPORT OF STATE ENGINEER. 97 Average Results Secured on Clay Loam Soils During- Four Years 1910 to 1913, Inclusive. 6"S T3 ^3 GCS . .2 Description of plots Crop 2 o ?! beu 3 u. * a. > 4iH- 55 970 .0650 .2480 2.6990 2.6790 1912 1913 11 13 .4910 8627 .5030 2284 .6210 7422 .6080 3854 .0380 0175 2.2610 2 236^ Average 0150 0140 6002 4408 7323 5744 0921 i 4688 Per cent of total 61 57 24.31 17.86 29 66 23 26 3 73 100 00 The above tables, as has been stated, include only plots that have demonstrated by the yields produced that they were cultivated and irrigated in the best possible manner, and the average amount applied during the 4-year period is shown at the bottom of the last column of each table, and is that amount which the author deems the best econ- 104 REPORT OF STATE ENGINEER. omic amount for the crop in question when planted on a medium clay loam on average South Idaho soil. The amounts of water tabulated in the above tables are the amounts that have been actually retained upon the fields in question, the waste water having been deducted. The grain table shows a Duty of almost exactly 1.50 acre feet per acre, of which .0098 acre feet, or .66 per cent are required during the last half of April ; .1385 acre feet, or 9.28 per cent during May ; .6849 acre feet, or 45.91 per cent during June; .5683 acre feet, or 38.10 per cent during July; and .0902 acre feet, or 6.05 per cent during August, there having been no water required for grains in Septem- ber during the period covered by the investigation. The alfalfa table shows a water requirement of 2.46S8 acre feet per acre, which is to all intents and purposes 2.5 acre feet per acre, of which .029 acre feet, or 1.18 per cent is required during April ; .6002 acre feet, or 24.31 per cent during May ; .4408 acre feet, or 17.86 per cent during June ; .7323 acre feet, or 29.66 per cent during July; .5744 acre feet, or 23.26 per cent during August ; and .0921 acre feet, or 3.73 per cent during the first one-half of September. It is believed that the two tables immediately preceding will be found the most valuable and most dependable of 'any that it is possible to include in this report, for they are a general summary of the four years' investigation in Idaho. Porous soils were included in the investigation during the seasons of 1910 and 1911, and a table which follows later, page 109, shows the average results secured on these soils. It is believed that the results secured are typical in every way of what might be expected from porous soils and that they may be safely used in such connection. It will be seen from the tables that the amounts required for al- falfa and the grains on these soils bear practically the same relationship to each other as they do when the crops are planted on the medium soils, and that a far larger amount of water is required for the successful irrigation of the crops than is required when they are planted on the medium Idaho soils. REPORT OF STATE ENGINEER. 105 COMPARATIVE AREAS DEVOTED TO DIFFERENT CROPS. In view of the great difference in the water require- ments of (a) the grains, potatoes and clean cultivated orchards, and of (b) alfalfa, the clovers and pasture, it is apparent that a knowledge must be had of the com- parative areas that will ultimately be devoted to these different crops before the proper Duty can be determined for any project. The acreages planted to these crops will, of course, de- pend in each case upon the soil, climate, proximity to market, and local conditions obtaining in each case, but is best determined by a survey of well developed projects that are and have been operating under normal condi- tions. It has frequently been assumed by those best in- formed in regard to irrigation conditions that most of Idaho's projects will be about equally divided between the two above classes of crops, but in order to demon- strate this matter more fully a census has been secured of the acreages of the various crops on the South Side Twin Falls Tract for 1912 and 1913, and of seven Boise Valley canals for 1911 and 1912 . A brief summary of this census is given in the following table. The census of the South Side Twin Palls Project was made by the ditch riders under the supervision of General Manager Harlan, and that of Boise Valley canals was secured by our own assistants. Table Showing- Comparative Areas Devoted to Different Crops. District u rt o> > Hay and Pasture Grain, Potatoes and Orchard Total acres Area acres Percent of total Area- acres Percent of total Twin Falls South Side Project Twin Falls South Side Project Seven Boise Valley Projects Six Boise Valley Projects 1912 1913 1911 1912 70,043 67,115 *26,2S3 24,492 47.55 44 95 *59.75 57.90 77,266 82,1% 17,684 17,804 194 ,950 52.45 55.05 40.25 42.10 147,309 149,311 43,937 42,2% 382,853 Total 187,903 49.08 50.92 Per cent of total * This area and percentage was somewhat above normal on account of the compara- tively larg-e amount of bottom land that was seeded to pasture under some of these canals. 106 &EPOBT OF STATE ENGINEER. In view of the fact that the percentage shown in the above table agrees with the best information obtainable along this line, it is considered that it is fair to assume that any normal project in South Idaho will ultimately be devoted to approximately equal areas of (1) the grains, potatoes and orchards, (2) alfalfa, clover and pasture, or crops requiring a similar amount of water. Assuming that this will be the case, the average Duty for a normal Idaho project should be found by averaging the proper and economic Duty for the two above named classes of crop on the particular type of soil involved. The follow- ing table has been constructed in this manner by averag- ing the Duty that has been determined for grain and for alfalfa on the medium or average soil of South Idaho for all four years of the investigation. Summary of Depths of Water in Feet Applied by Months to One Hun dred and Seventy-one Selected Fields of Grain and Alfalfa on Medium Clay and Sandy Ivoam Soils. Altitude ranging from 2400 to 5000 feet. Seasons of 1910, 1911, 1912, 1913. Crop c of Ap ril May June Julj r Aug-. Sept. c "3* % I s - 1-15 16-30 1-15 S Alfalfa 1910 1910 15 31 .0600 .0210 .5540 3210 .7390 6000 .6530 5460 .6070 0780 .0650 2.6990 1.5450 Alfalfa Grain 1911 1911 13 30 .0350 .4930 0270 .2930 6540 .9130 4780 .6970 0100 .2480 2.6790 1.1690 Alfalfa Grain . . . 1912 1912 11 25 .4910 .5030 9420 .6210 6550 .6080 0460 .0380 2.2610 1.6430 Alfalfa 1913 13 .8627 .2284 .7422 .3854 .0175 2.2362 Grain . 1913 33 0392 .2062 .5434 .5941 .2268 1.6097 Average .0075 38 .0119 60 .3693 18 65 .5628 28 42 .6504 y> 85 .3323 16 78 .0460 2 32 1.9802 100.00 The above table is a general average of the results that have been secured on the average soil of South Idaho dur- ing the entire four years' investigation, and it is considered that it is by far the most important table included in this report. It is in reality the "meat" or final result of the entire four years' Duty of Water Investigation and, as the soU in question is an average of that which is, or wilJ be, included in at least 75 per cent of Idaho's irrigation projects, and probably in the same per cent of the projects in many other states, it is believed that this table will be used far more than the following one which shows the aver- age amounts applied to porous soils. REPORT OP STATE ENGINEER. 107 AMOUNT OF WATER REQUIRED EACH MONTH OF THE IRRIGATION SEASON BY A PROJECT DEVOTED TO EQUAL AREAS OF GRAIN AND HAY ON MEDIUM CLAY OR SANDY LOAM SOIL. As this table includes the results of 171 selected tracts of this particular type of soil covering a period of four years, thus effectively eliminating the individual differ- ences of the seasons, of irrigators and of the tracts them- selves, it is considered that the results contained in it will be found to be very dependable. It shows that a project devoted to equal areas of (1) grain, orchards, and general root crops, and (2) hay, in- cluding alfalfa, clover, timothy and pasture on average South Idaho soil should furnish sufficient water so that an average of 1.98 acre feet can be retained on each and every irrigated acre during the season. Of this amount, which is to all intents and purposes an annual or seasonal Duty of 2 acre feet per acre, exclusive of the precipitation, 0.0075 feet in depth or 0.38 per cent will be required dur- ing the first half of April; 0.0119 feet in depth or 0.6 per cent will be required in the last half of April ; 0.3693 feet in depth or 18.65 per cent during May; 0.5628 feet in depth or 28.42 per cent during June ; 0.6504 feet in depth or 32.85 per cent during July; 0.3328 feet in depth or 16.78 108 REPORT OF STATE ENGINEER. per cent during August; and 0.0460 feet in depth or 2.32 per cent during the first half of September, making a to- tal of 1.9802 acre feet per acre, or 100 per cent for the season. The above amounts are based strictly upon the crop needs as shown by the Duty of Water Inves tigation, and includes nothing for stock water or that which may be required for domestic purposes or for losses in conveyance, nor is there any included for late fall or winter irrigation. If the data in this table are to be used in alloting water to an irrigation project this factor must be taken into consideration, if water is to be used for the above mentioned purposes. This table shows that there is small need for water either earlier than May or later than August; and that in all of the tracts considered there has been no need for water during the four years of the investigation by either alfalfa or grain during the last half of September. It shows also that over 61 per cent of the total water re- quired during the season is required in the 61 day period during June and July. This table will be found very use- ful to those called upon to design storage projects, as a variety of curves may be worked up from it, which, taken in connection with the hydrograph of the discharge of the stream from which the supply is to be derived, will show how much of the water it will be necessary to store. It will also be of great help in the designing of pumping plants, and particularly in determining the size of the var- ious pumping units that should be installed. The table shows conclusively that any large pumping plant should consist of more than one unit, and possibly as many as three or four, for a unit that could economical- ly supply the maximum demand during June and July could not possibly be economically operated with the de- creased demands of May and August. This feature must always be given consideration. The table seems to prove conclusively that the uniform continuous flow method of delivery is exceedingly waste- ful, for if a right called for a uniform continuous flow throughout the season with an allotment per acre of suf- ficient size to deliver the required amount during June and July, a large proportion of the amount delivered could not be used economically, and would be wasted during the months of April, May, August, and September. While if. REPORT OF STATE ENGINEER. 109 on the other hand, the uniform continuous flow were of the size required to deliver the 2 acre feet required during a 6 months' or even a 4 months' irrigation season, there would still be more water than is actually required during the early and late part of the season, and considerably less than is required during the months of June, and July, when 61 per cent of the total season's supply must be de- livered if profitable returns are to be expected. The following table gives a general summary of the re- sults that have been obtained upon the porous sandy and gravelly soils. This table has been constructed by aver aging the Duty that has been determined for grain and al- falfa on these soils during the first 2 years of the investi- gation, there not having been a sufficient number of tracts on this type of soil experimented upon during the last 2 years of the investigation to be included in such a sum- mary table. Summary of Depths of Water in Feet Applied by Months to Thirty- one Selected Fields of Grain and Alfalfa on Porous Sandy and Gravelly Soils. Altitudes ranging- from 2600 to 5800 feet. Seasons of 1910 and 1911. Crop c o C0 ^ Ap ril May June July Aug-. Sept. u s= ,_, o Ss. z & 1-15 16-30 gl Alfalfa 1910 7 5310 1 1200 1 6910 1 9570 1 1310 6 4300 Grain 1910 10 .0290 1.4430 .6550 .3580 2.4850 Alfalfa 1911 6 .1820 .9160 1.8430 l.llfO 2.2650 .2560 6.5770 Grain 1911 g 8980 1 0570 9430 2 8980 Average .1782 .5163 1.4687 1.1960 1 . 1743 .0640 4.5975 Per cent of total . 3 88 11 23 31 9S % 01 25 54 1 39 100 00 This table shows that porous soils require a larger amount for their efficient irrigation than the medium soils, and indicates that a Duty of approximately 4.6 acre feet per acre per annum will be required, of which 3.88 per cent will be required during the last half of April ; 11.23 per cent will be required during the month of May; 31.95 per cent during June; 26.01 per cent during July; 25.54 per cent during August; and 1.39 per cent during the first half of September, making a total of 4.5975 acre feet, or 100 per cent during the season. The preceding tables showing the average Duty that has been arrived at for projects with either medium or porous soils are considered the most important in the report; 110 REPORT OF STATE ENGINEER. These and the many factors which have a bearing upon the Duty of Water will be discussed more thoroughly later in the report. INVESTIGATION OF USE OF WATER UNDER COM- PLETE CANAL SYSTEMS IN BOISE AND UPPER AND MIDDLE SNAKE RIVER VALLEYS. It is considered that the investigation which has been carried on will furnish a very accurate idea of the proper and economic field Duty for the different soils, but it has been realized that, in addition to this, a knowledge of the losses that are usually experienced in transmitting and delivering the water must be had before it will be pos 1 - sible to design an efficient and economical project. In order to secure a better knowledge of this factor it was decided to extend the investigations by measuring the total amount of water diverted by several typical large canals and then secure the acreage under them devoted to the different crops, and in this way determine the gross amount that it is found necessary to divert for the irri- gation of large areas under normal conditions, where waste water and that used for domestic purposes, etc., would all be considered. It had been planned to do this work during 1912, along with a lesser number of the usual Duty of Water experi- ments, as a rounding out of the entire investigation, but it was found in the fall of 1911 that the local branch of the U. S. Reclamation Service had been making a careful measurement of all water diverted by the principal canals of the Boise Valley during the season, and it was decided to start this line of investigation at once, provided a suit- able arrangement could be entered into with the U. S. Reclamation Service for securing these measurements. These arrangements were perfected and an agreement was entered into between the two departments, whereby our department was to make a careful canvass of the crop acreages under the canals and exchange the data so col- lected with the U. S. Reclamation Service for the discharge tables that had been secured by them. Accordingly, an experienced man was placed in the field, who made a careful and painstaking canvass of the areas devoted to the different crops, together with the un- irrigated area, and such other data as was thought neces- sary. This crop census was made of all lands under the REPORT OF STATE ENGINEER. Ill following canals : Settlers', Farmers' Co-operative, River- side, Farmers' Union, Pioneer, Eureka and Boise Valley. On account of the great expense that would have been involved in making a survey, the acreages were obtained by a careful and systematic house-to-house canvass or census. It is believed that this canvass was especially ac- curate and fully as reliable as any stadia survey that could be made, for the following reasons : (1) A much larger area could be taken into consid- eration on account of the expense that would be involved by a survey, which increase in area, it is believed, materially reduced the percentage of error from all causes. (2) Accurate maps of the canal systems were secured, and as the farms were regular in shape and not cut up by waste land, the total area under the canals was easily se- cured. (3) The areas devoted to individual crops were ob- tained from the farm operators on the ground, and as the areas of the individual crops had to equal the total area of the farm, in each case a very good check was ob- tained upon the accuracy of the canvass. Water Measurements. All water measurements 1 during 1911 were made by the local branch of the U. S. Reclamation Service. Those of 1912 were made by our own hydrographers. The discharge of the canals has been calculated from daily gauge read- ings and rating curves, which were made up from a large number of current meter measurements made by from two to six hydrographers at each station. These rating sta- tions were very carefully selected, and as a very large number of careful ratings were made at each station, it is believed the discharge tables given herein are very ac- curate. The water measurements of the South Side Twin Falls Canal were secured from the local branch of the TT. S. Geological Survey, and the crop census from General Manager Geo. Harlan, who had caused a census to be taken during both years by his ditch riders. A brief description of each canal system follows, together with the data that were secured from it during the seasons of 1911 and 1912. Riverside Canal. The Riverside Canal diverts water from the south side of the Boise River just above Oaldwell. This canal irri- gates approximately 9,000 acres of bench lands, consisting 112 REPORT OF STATE ENGINEER. principally of the typical volcanic ash or clay loam soil common to the greater portion of South Idaho. Farmers' Co-Operative Canal. The Farmers' Co-operative Canal diverts water from the north side of the Boise Eiver just above Caldwell, the the headgate being located almost opposite that of the Riverside Canal. The canal has a total length of about 28 miles and irrigates bench lands entirely. The soil under this canal varies from a clay loam to a loose granite sand. Farmers' Union Canal. The Farmers' Union Canal diverts water from the north side of Boise River near the Soldiers' Home, a short dis tance below Boise. The soil under this canal is mostly volcanic ash or clay loam, there being a small percentage of somewhat sandy soil. This canal is approximately 20 miles in length and irrigates approximately 7,000 acres of land. Settlers' Canal. The Settlers' Canal diverts its water from the south side of Boise River within the city limits of Boise and irrigates approximately 12,000 acres of clay loam bench land in the vicinity of Meridian on the south side of Boise River. Boise Valley Canal. The Boise Valley Canal diverts its water from the Farmers' Union Canal about one mile below the intake of that canal and furnishes water for approximately 2,600 acres of sandy loam bottom lands. The ground water under practically all of this land rises every summer and averages from two to four feet from the surface during the irrigation season. Pioneer Canal. The Pioneer Canal diverts water from the north side of the Boise River about one mile southeast of Palmer Station. This canal is only approximately three miles in length and furnishes water for approximately 1,265 acres of sandy loam Boise bottom lands. The land under this pro ject is fairly well irrigated during the irrigation season by sub-irrigation from the rise of ground water. Eureka Canal. The Eureka Canal diverts water from the south side of REPORT OF STATE ENGINEER. 113 Boise River immediately below the headgate of the Phyllis Canal. This canal supplies water for approximately 2,000 acres of Boise bottom land and is very similar in every respect to the Pioneer Canal. Randall Canal. This canal diverts its water from the Burgess Canal 7 miles southwest from Rigby in the upper Snake River Valley. It is about five and one-half miles in length and furnishes water for approximately 4,000 acres. The lands under the canal have a uniform topography and the soil is of a very porous, gravelly nature, common to 30,000 or 40,000 acres in that vicinity. Clark and Edwards Canal. The Clark and Edwards Canal diverts water from the "Big Feeder" about six miles southeast from Rigby. This canal is approximately four miles in length and furnishes water for about 4,000 acres of very gravelly land. South Side Twin Falls Canal. This well known canal diverts water from the south side of Snake River at Milner through a main canal with a capacity of 3,200 cubic feet per second, and 25 miles long. The main canal branches into two main branches at the end of the 25 mile section, each branch being ap- proximately 35 milesi in length. The South Side Twin Falls Project consists of approximately 200,000 acres of slightly rolling clay loam or lava ash soil situated on the south bank of Snake River and east of Salmon River. The project has a rather uniform topography with a slope averaging 50 feet per mile to the northwest. The soil varies in depth from 2 to 40 feet with a probable average of 6 to 10 feet, being underlaid with lava rock, there being no intervening stratum of gravel or other porous material. The first irrigation water was applied to this project dur- ing the seasons of 1905 and 190f>, tho following tables shov-ino- the amount cultivated during the seasons of 1912 and 1913. 114 REPORT OP STATE ENGINEER. Table Showing Comparative Area Devoted to Different Crops, of Areas Actually Irrigated Under Ten Different Canals. Name of canal rt V (H Hay Pasture Grain Orchard* Total acres 7425.50 6898.50 12435.25 13062.41 6842.70 7144 42 11819.80 11755.00 2225.49 2287.00 2062.00 1126.54 1W8.74 3255.00 1362.50 147309.00 149311.00 Acres I! Acres > a i a >- j>> c 1-1 bi. a < a 1 Oct. 1-15 16 30 1-15 16-31 Riverside *, 1911 1912 1911 1912 1911 1912 1911 1912 1911 1912 1911 1911 1912 1912 1912 1912 1913 0.08 0.11 0.04 0.00 0.14 0.25 0.04 0.00 0.14 0.00 0.00 0.11 0.14 0.00 0.00 0.10 0.09 0.43 0.63 0.38 0.08 0.48 0.68 0.16 0.01 0.27 0.00 0.05 0.40 0.00 0.00 0.00 0.14 0.11 1 1.40 1.74 1.31 1.07 1.25 1.32 0.42 0.49 0.63 0.46 0.38 0.91 1.12 0.00 0.31 0.60 0.83 0.84 1.46 1.98 1.36 1.26 1.41 1.23 0.72 0.69 0.59 0.50 0.33 0.97 1.62 1.58 2.59 1.10 1.12 1.21 1.54 1.99 l.lb 0.94 1.25 1.07 0.71 0.70 0.64 0.68 0.34 1.09 1.03 2.25 3.00 1.23 1.25 0.79 1.19 0.44 0.58 0.55 0.53 0.46 0.54 0.42 0.38 0.35 1.01 0.98 1.99 2.67 1.13 1.21 0.79 1.23 0.36 0.56 0.45 0.45 0.42 0.34 0.30 0.37 0.34 0.83 0.82 0.81 2.04 0.61 0.73 0.50 0.62 0.28 0.17 0.13 0.00 0.11 0.10 0.12 0.00 0.03 0.12 0.31 0.25 0.34 0.22 0.20 0.15 0.00 0.19 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00 0.16 0.17 0.05 7.14 9.49 5.52 4.76 5.66 5.53 3.04 2.87 3.11 2.39 1.84 5.44 6.02 6.88 10.95 5.29 5.71 Riverside * Farmers' Co-operative... Farmers' Co-operative... Farmers' Union Farmers' Union . Settlers' . Settlers' Boise Valley Boise Valley Kureka Pioneer Pioneer Randall , Clark and Edwards South Side Twin Falls. South Side Twin Falls. Average for month... .... 0.08 0.22 1.23 0.89 0.67 0.20 j 5.39 Per Cent of Season's Diversion 1.49 4.08115.60 1 22.43 22.83 16.5 12.43 3.71 0.93 100.00 The Boise Valley canals included in the foregoing in- vestigation are fairly well distributed throughout the valley, supply water to a large percentage of its irrigated area, and there is no doubt but that the tables represent the present average use of water in the Boise Valley. The Clark & Edwards and the Randall Canals lie in the upper Snake River Valley but are not typical of the majority of the canals in that district, for the soil under them is more gravelly than the district as a whole averages. These canals and the use of water under them, however, are typi- cal of those supplying water for some 40,000 or 50,000 acres in the vicinity of Rigby. The use of water under the South Side Twin Palls Canal is probably typical of the majority of Idaho's largest irrigation projects, par- ticularly of those which have a large and adequate water supply. 116 REPORT OF STATE ENGINEER. It is regretted that the data secured do not throw any light on the losses that have been experienced by seep age under the projects investigated. The study of the data included in the tables makes it quite evident that this factor is much greater than is usually believed. From a study of the seepage measurements which are described later in this report it would seem that the transmission losses of Idaho canals range from 20 per cent to as high as 50 per cent of the water diverted. The water supply in the Boise River is usually plentiful for all canals until the middle of July, after which time a reduction in the amounts diverted is made by the water master on all except those having the earliest priorities. For this reason the amounts shown as having been di- verted by the Boise Valley canals during August, 1911. are unquestionably from 20 to 30 per cent below the amounts needed. The flow* of the Boise River, however, was above normal during August, 1912, and it is believed that the canals during that month diverted nil of the water that was actually required. A comparison of the above tables of canal diversions with the preceding curve and Duty tables strikingly emphasize many interesting factors: (1) That where water supply is plentiful the average canal diverts more water than is needed for economical irrigation, both at the beginning and end of the irrigation season. (2) That practically the entire need for water falls during the four months from May to August, inclusive. (3) That the actual diversion of average canals is far greater than many have realized, indicating that the loss from seepage, evaporation, general waste and careless use as well as the amount required for stock and domestic purposes is far ereater in actual practice than has usually been acknowledged. A careful study of the above data taking into consideration the fact that the canals investi- gated represent an average or a little better than average use of water, makes it evident that there is ^rave danger of allotting insufficient water to many of our future projects. REPORT OF STATE ENGINEER. AMOUNT OF WATER USED ON TYPICAL FARMS UN- DER THE RIDENBAUGH CANAL IN THE BOISE VALLEY DURING THE SEASON OF 1912. It is believed that the average results of, the Duty of Water Investigation with its variation of water on ail tracts will give the correct Duty, but as only approximate- ly one-third of the tracts involved have been handled ex- clusively by the owners themselves it is realized that the results that have been secured may not furnish an accu- rate idea of the average use of water in the State at this time. In order to show the average use of water in a typical district and to furnish data to strengthen the other more exact Duty of Water experiments where the water had been varied and measured very carefully, it was de- cided to detail one assistant during the irrigation season of 1912 to the measurement of the water used by the farmers on as many farms as possible in a typical district. The district selected was that lying under the Kiden- baugh Canal within a radius of four miles of Meridian. Care was used to include as many as possible of the staple crops on the average farms of the district, and as much was included as one man could cover, reading all weirs in the supply ditches twice daily. The waste water was not measured, but all of the areas were surveyed very care- fully. There were no restrictions whatever placed upon the users, and it is believed that the customary amount of water was used, and that an average crop was produced. The data secured are given in the following table: 118 REPOET OF STATE ENGINEER. Fable Showing- Amount of Water Used on Typical Farms Under the Ridenbaug-h a Boise Valley Canal During- the Season of 1912. Crop Remarks 1 Alfalfa 2 Alfalfa. 3|Alfalfa 4 1 Alfalfa. 5|Alfalfa til Alfalfa 7 1 Alfalfa 8|Alfalfa 9 Alfalfa Alfalfa Alfalfa 2IAlfalfa 3 1 Alfalfa 4 Oats 5 Oats 6 Oats 7 Oats 8 Oats 3.50 5.31 7.06 26.25 6.78 7.68 10.32 7.24 5.85 3.85 1.42 2.65 15.67 30.33 19.32 33.70 27.96 14.58 5-14 9-18 5-13_ 8-29 109 5-15 9-2 5-16 9-8 5_21_ 9-9 5-18 9-14 5-26 9-15 113 91 Oats and 0| Wheat I l| Wheat 2| Wheat i SlWinter Wheat Wheat. 11.90 .52 10. 11.24 l|Clover 5 1 Clover 3|Timothy 7|Orchard Grass 3|Pasture DJPasture 3i Pasture L|Pasture * I 21 Apple Orchard . . 3| Apple Orchard .. tj Apple Orchard .. 51 Apple Orchard .. 5| Wheat and barley I 5-21 8-: 5-16 8-20 5-18 9-25 5-19 7-11 5-20 8-25 5-16 9-21 128 10 5.6619 .3961 .2617 3747| .7999 .0183 3.0995 .7191 .1101 2.2104 120 (i :j. (i a. t>3. 63. 64. 73! 52. :;:j. 34.1 I 6-17 7-181 32 6-12 7-28 6-23 7-28 6-26 7-17 6-26 8-10 6-8 7-26 6-20 8-5 6-5 7-28| 54 7.4 _ 7-171 14 5-30 6-4 5-16 9-25 133 5-18 9- 5.15 9-20 129 5-10 9-23 137 5-1110-1 5-8 _ 9-25 141 5-12 9-12 124 5.9 _ 9-26|141 I 7-6 8-29| 55 6-22 9-7 7-8 9-5 7-6 9-1 5-29 7-19 .3187 .4656 21. ,0445 55.00 bu. 3 1.7293 53.67 bu. 1.0853 51.93 bu. 2 0.8763 32.19 bu. 1.0869 40.81 bu. 3572 44.00 bu. 1993 17.92 bu. 8864 44.00 bu. 7586 18.00 bu. 3567 6594 5761 9250 144 10 2.6943 8111 2770 73. 65. 5.92 tons 4.67 tons 4.67 tons 3.19 tons 3.63 tons 3.63 tons 3.58 tons 3.25 tons 3.42 tons 3.00 tons 3.25 tons 1.92 tons 3.05 tons Two cuttings. Two cuttings, carelessly irrigated. 10.618522.42 bu. 2.57 tons 5.74 tons 2.74 tons 2.18 tons 9 3 1 3 1.5505 217. 94 bxs. 30. .4493 .3365 .5505 .7081 .4310 0.8969 36.95 bu. Poor land and poorly cared for. Very much neglected. Poor stand. Two crops. One crop (yield baled). One cutting. Blue grass and white clover. Blue grass and white clover. Three years old. One-half bearing. Clean cultivated, 2 and 3 years ol< Clean cultivated, 2 and 3 years ol( It is realized that the data, secured and tabulated in the above tables are less accurate than those of the major in- vestigation, but in view of the comparatively large area involved, the fact that one man gave his entire time to the investigation during the season and that this man had the entire co-operation of all of the owners, it is believed that the data, secured are accurate enough for all practical purposes, and that they will furnish a clear idea of the REPORT OF STATE ENGINEER. average use of water in a typical irrigated section of Idaho. There was no U. S. Weather Bureau Station located at Meridian, but the precipitation that occurred from April to September, inclusive, was without a doubt approximate- ly the same as that of Boise, which is only 9 miles away. This was 8.25 inches. It is believed that irrigation is as highly developed, and that water is of as much value, in this locality as it is in any other representative district of the same area in the State. It is also believed that the farmers use the water as carefully and waste as little as they do in any other dis- trict of the same magnitude. The average of the amounts used by all of these irrigators was 2.56 acre feet per acre, the water having been measured in each case within a short distance of the boundaries of the farms in question. The above use of water agrees very closely with the re- quirements shown by the major investigation, for if 21 per cent of the amount delivered and applied was wasted, the amount retained would have been almost exactly 2 acre feet per acre. The crops produced that season in the district under observation were fair and normal in every respect. It was the belief of the owners that they could not have well used any less water, and that if less water had been used the yields would have been materially re- duced. It is therefore believed that this supplementary in- vestigation furnishes strong and added proof of the adequacy of, and the necessity for, a water right of suf- ficient size to permit of the retention of 2 acre feet per acre upon clay loam soils. INVESTIGATION OF THE AVERAGE USE OF WATER BY THE SETTLERS OF THE SALMON RIVER PROJECT. Three assistants were detailed to the Salmon River Project during the season of 1913, whose entire time was devoted to the measurement and variation of the water applied to 12 tracts of the staple cropsi, each of an ap- proximate area of 15 acres. Each of these tracts was divided into 3 approximately equal parts. The investiga- tion as above outlined was carried on in order to ascertain the best Duty for the various crops on the project as a whole, for it was believed that the variation of the water would throw new light upon the actual water requirements of the soils and crops. 120 REPORT OF STATE ENGINEER. In order to supplement the experiments where the water was varied and determine the average use of water by the Salmon River settlers and to throw as much additional light upon the proper Duty of Water as possible, one man was detailed during the same season to the measurement of the water applied by the owners to parts of 12 typical ranches well scattered over the project. This was done with 16 automatic water registers, which were installed on weirs in the feed and waste ditches leading to and from each plot. These water registers consisted essentially of an eight day clock and a revolving cylinder upon which a paper record sheet w^as placed. The variation of the height of the water flowing over the weir and the movement of the clock traced on the record sheets an accurate and con- tinuous record of the height of the water flowing over the weirs, each record lasting an entire week. Wherever a tract of sufficient area could be picked out so that all of the feed water applied to and all of the water wasted from the tract could be measured by two water registers, this was done, but in cases where the area involved was too small to justify the expense, or where the water wasted from the field in question through 2 different ditches, the waste from the fields was not measured. With one or two exceptions it is believed that the results se- cured show up the average use of water on the Salmon River Project during the season of 1913. On account of the size of the tracts involved and the wide area which they covered it was found impractical to weigh the yields produced. These were determined from the records of the automatic weighers attached to the threshing machines which threshed the grain, and by measuring the alfalfa in the stack. While the determinations of yields by the above methods were not absolutely accurate, it is believed they are suf- ficiently so for all practical purposes. All of the areas in- volved were carefully surveyed with transit and chain, so that part of the following table which shows depths ap- plied per acre is believed to be very accurate. REPORT OF STATE ENGINEER. 121 CO 00 <) II ! ^ S2 1 . -d g- . co to s,? s $1 H a & 3 g> a a 33 00 C p (D P s^- c?H ^ | | a i Number Showing 1 B; < p 2 o* 3 a 2.S (y tfj a-s l> - 2 c Vt ^ a o a Gq Q Area acres Applied Wasted ?. 4>.oi to to co Depth in feet or acre ft. per acre applied to land siss 2 r && o'er * 122 REPORT OF STATE ENGINEER. INVESTIGATION OF USE AND DUTY OF WATER AND COST OF PUMPING UNDER ELECTRICAL PUMPING PLANTS IN THE VICINITY OF WEISER AND PAYETTE DURING THE SEASON OF 1913. Water is now being pumped in Idaho for the irrigation of many thousands of acresi, but there are still many op- portunities for expansion along this line. This is particu- larly true of the territory along Snake Eiver from Hager- inan as far down as Huntington, Oregon, a distance of nearly 250 miles, there being available even at low water fully 3,000 cubic feet per second of unappropriated water in this section of Snake River. This water cannot be di- verted by gravity on account of the comparatively high banks and flat grade of the river, but there is considerable good land adjacent to the river upon which this water might be, and is being pumped with lifts, varying be- tween 50 and 200 feet. The lands adjacent to Snake River, however, are not all of those upon which pumping may be found feasible, for the best land in many projects lies immediately above the high line canals, where in many in- stances rather large acreages could be covered with com- paratively small lifts. Idaho has great water pow r er re- sources, only a small part of which have been as yet de- veloped, and considering this fact, and the availability of land and water, it appears as though this were a most fa- vorable field for irrigation pumping. The entire Duty of Water investigation, up until 1913, had been carried on under gravity canals where there was no particular incentive to save water, and it seemed as though the time were opportune to conduct two investiga- tions in one by determining (1) the Use and Duty of Water under a number of pumping plants where there was a strong underlying incentive to secure the highest possible Duty, and (2) to determine the costs of pumping at the same time. There were 163 different electrically driven ir- rigation pumping plants being operated during the season of 1913 in the territory adjacent to the Snake River be- t\veen Caldwell and Huntington, and it was decided to as- sign one assistant to this territory who should be furnished with a motorcycle and who would determine by means of weirs, water registers and watt meters the amount of water pumped and electricity used, under as many as possible of the smaller or medium sized pumping plants in that vicin- REPORT OF STATE ENGINEER. ity. After looking over the territory a number of owners and operators were interested in the investigation and some 20 plants in the vicinity of Payette and Weiser, Idaho, and Ontario, Oregon, were selected for the season's test. Some of the plants selected were paying for their power by the meter rate, and some were paying a flat rate based on the horsepower of their motors. The flat rate plants did not all have meters and it was not possible to determine the exact amount of current consumed by them, but the cost of the service to the farmers for the season, however, based on the amount paid to the power company, was easily determined, and the following tables give the re- sults that were secured. The cost of pumping, as given in these tables, includes only power charges, nothing having been added for depreciation, attendants, etc. 124 REPORT OF STATE ENGINEER. 1OOJ 3J3B jooj jaj ;ooj ajDB + -f + ifc S& f, r* i-H + + a s * rorr " + r r r 10 r- 8 2 $888338888883? o o -e -a rt J a 3 < 0- 9JIDB J8J ? 8 58 S 38 Pi otal No.hrs May to Sept. inc., 3,672 UOS139S jo ^naD aaj + + + ^J i^ ^ S 2 J^5 UOSB9S J3UI -anp paj-eaado sanoq Ov t r^ _ 3 I ft rr r-t s g I S84DV * 8 8 9 iri g i^ * C* rO * IH jaaj jjj I 5 H S 1 C5 W O O O O 2 lO.uod aSJOH s ; ; a 8 c : Ills ll bo C 3 . j> < < O -H 3 - REPORT OF STATE ENGINEER. 125 The investigation as a whole showed up many interest- ing factors in connection with the pumping of water for irrigation purposes, principal among which are: (1) That greater care should be used in the designing and installation of the small plants so as to reduce the friction of shafts and belts, of water in the pipes and all other losses to a minimum. Pumps direct connected on the same shaft with the motor and bolted to the same base are recommended. Suction pipes should be as short as possible and intakes should be screened to keep out all trash. Discharge pipes should contain as few sharp turns as possible, and there should be no 90 degree angles in them. These pipes should also be of a rather large bore or diameter so as to reduce friction losses as much as possible. The inefficiency of, and abnormal amounts of power consumed by the small "stock" pumps that might or might not have been running at the speed or pumping against the head for which they were best designed, was strikingly emphasized. The design of hydraulic ma- chinery, and particularly centrifugal pumps, is a compli- cated problem at the best, and the investigation as a whole, as will be seen from some of the abnormal pumping costs, seems to emphasize the desirability of having all but the smaller sizes of installation designed and installed by a .hydraulic engineer who is known to be competent. (2) It is not possible, generally speaking, to opera re pumping plants continuously. It should, however, be pos- sible to operate a small, well designed plant at least 75 per cent of the time during the season. With the present power rates it is not economical for the consumer to own a plant any larger than would be required to pump the necessary water by operating three- fourths of the time. (3) The charges for power that were paid by the con sumers for the small or average size pumping plants for a five months' season was $28.00 per horse-power for plants up to 20 horse-power; $26.00 per horse-power for plants from 20 to 40 horse-power; $25.00 per horse-power for plants from 40 to 75 horse-power. Tho above was the flat rate charge per horse-power. The other class of con- tract was a combination of the meter and flat rate as follows : f 10.00 per horse-power service charge for a five months' season, plus two cents (2c) per kilowatt hour 126 REPORT OF STATE ENGINEER. for all current consumed with a $20.00 per horse- power minimum charge for the season. The results of the investigation seem to indicate that the development of new lands in Idaho at the present time will not withstand the charges necessary when water is raised over 150 feet, and not over 100 feet would be recom- mended in many cases except with the larger installations where a much higher efficiency can be secured. The abovo seems true in most cases for lifts above 100 feet, for the annual maintenance, which includes (a) expense of at- tendants, including ditch riders; (b) repairs and general depreciation of plant; (c) interest on original cost; (d) charges for power, lubricating oil, etc., will be too excessive for the development of raw land except in exceptional cases. Old bearing orchards, vineyards and other highly remunerative crops will necessarily withstand greater power charges and consequent greater lifts than the de- velopment of raw land. It must be borne in mind that the man under the pumping plant with his high annual main tenance charge must in almost all cases compete with his neighbor under a gravity canal with a consequent lesser charge for annual maintenance. The results of the investigation as a whole were quite satisfactory, but owing to the flat rate power charges and the $20.00 minimum clause in the meter rate contracts, it was found that there was no more incentive to save water* than under some of the gravity canals. Some of the users were particularly wasteful of their water. This was very disappointing, but in all probability added time will give both the farmers and the power company experience that will tend to better the conditions that now exist. The major factor brought out by the investigation was the de- sirability of better designed and installed equipment. This will be imperative in order to make a permanent suc- cess of irrigation pumping. Subsequent mechanical efficiency tests showed that the over all efficiencies of the plants in the Pavette district ranged from less than 25 per cent to as much as 75 per cent. The majority of the plants included in the 1913 in- vestigation above outlined were developing efficiencies of loss than 40 to 45 per cent, showing that the farmers were pa.yinc: nearly twice as much power charges as should have been necessary for the amount of water pumped. The REPORT OF STATE ENGINEER. 127 fault, however, was invariably in the poor design and faulty installation of the plants, rather than with the rate paid for power. The farmer must be made to realize that the best designed plant of the best possible construction is by far the cheapest in the end, though the initial cost may be 50 per cent greater than some plants might be installed for. AMOUNT OF WASTE OR UNIRRIGATED LAND IN A TYPICAL PROJECT. The total amount of water required by any project, as has been outlined previously in this report, depends upon at least four factors: (1) the Duty of Water at the land; (2) the amount of transmission loss between the point of diversion and the land to be irrigated; (3) the amount of loss from reservoirs; aud (4) the proportion of a project that is ultimately irrigated. The above factors must all be given serious consideration when designing any irriga- tion project, aud as far as all practical purposes are con- cerned, are of equal importance, for to err or miscalculate in regard to any one of them might in some cases be the cause of the failure of the project. The fourth factor, the proportion of a project that is ultimately irrigated, is considered to be fully as vital and important as any of the others which have a bearing upon the amount of water required for a project, for it would unquestionably be impossible to design any project proper- ly and economically without a knowledge of this factor, even though all of the other factors involved were accurate- ly known. So far as the individual user is concerned, it may be found that the irrigation company will be re- quired to deliver him water on the basis- of the number of acres actually owned and upon which he pays maintenance without regard to how much of his land is devoted to roads and waste or other uncultivated area. Yet so far as a project as a whole is concerned, it seems quite evident that the total amount of waste and unirrigated land in the project will always be a dominant factor, for even though the individual is delivered water on a basis of the area actually owned, water will not be used on the waste places, and the water for the balance of the project will be ma- terially increased thereby. It has been roughly estimated by many engineers in the past, there having been no accurate data in regard to the 128 REPORT OF STATE ENGINEER. subject, that 20 per cent of a normal project would always be unirrigated from a variety of causes. The author has always believed this estimate to be too high for Idaho projects, for wherever large bodies of high land or rough, rocky land have existed they have been eliminated from the project at the outset. It has not seemed possible that the ordinary waste or unirrigated area, consisting of county roads, railroad rights of way, ditch rights of way, fence rows, corrals, stack yards, small high spots and other wasites of all kinds has amounted in any one year on a well developed project to as much as 20 per cent of the total area for Avhich water rights were provided. Realizing the extreme importance of this factor and the utter lack of dependable data in regard to it, it was decided some two years ago that this factor should be determined for Idaho conditions. It was decided that the determination should be made by means of an actual survey of typical irrigated land, in contiguous bodiesi located in at least two different typical Idaho irrigation projects. After considering several projects and looking over a large amount of land, two localities were selected as being typical of Idaho's irrigation projects. One of these was in the Boise Valley in the vicinity of Meridian, where land had been farmed for fifteen or more years, and the other was in the heart of the South Side Twin Falls Project, in the vicinity of and surrounding the town of Kimberly, five miles east of Twin Falls. Twenty sections were surveyed in a contiguous body lying immediately north of and adja- cent to the town of Meridian, and skirting the Boise Valley bottom lands on the south. The land surveyed was ail bench land and was typical in every respect of the better class of irrigated land in the Boise Valley. THie other area surveyed consisted of six sections entirely surrounding, but one-fourth of a mile removed, from the Kimberly townsite. This land was typical in every respect of the better class of irrigated land on the South Side Twin Falls Project. Land immediately adjoining the towns was not included in the investigation, for it was divided into such small holdings that it was considered not typical of a project as a whole. Sections were frequently encountered during the survey that seemed to vary somewhat from the typical on account of too much or too little waste land, but as the specific area to be surveyed had been predetermined as typical these areas were always included along with the rest so as to REPORT OF STATE ENGINEER. 129 eliminate the personal equation of the men who did the actual field work. These surveys were made with the transit and chain. The notes were platted on detail paper to a scale of 200 feet to the inch and the areas were determined with a polar plani- meter. A reasonable amount of care was always used, and while it is known that the areas included in the table are not exactly accurate, there is no doubt but that they are accurate enough for all practical purposes. The total areas devoted to each of the various irrigated crops 1 and the total areas devoted to the various non-irri- gated areas were segregated and are shown in the table which follows. As most of the surveys were made during the fall and spring, or non-irrigation season, it has not been possible to determine the exact amount of land that was unused or fallow for a variety of reasons, and there is no column set aside for this class of land in the table. The field men who made the survey insist that there was none, and that whatever fallow land that existed in the entire area was still devoted to sage brush that could and would be cultivated and irrigated at no distant date. It is believed that the total area surveyed, consisting of 1 6,065.21 acres, is large enough so that a dependable esti- mate for similar projects may be based upon it, for the total area, considered is in itself as large as some irrigation projects, and is one-quarter or one-half as 1 large as the ma- jority of them in the West today. It is realized that there is always a small amount of fallow land in any project that may be uncultivated for a year or two for a variety of rea- sons, such as sickness or death of the owner, failure to find a renter, trouble over water rights, or ditch rights 1 of way, or the breaking of ditches. While it is realized that such fallow land will always exist in all projects, it is believed that the per cent devoted to it will necessarily be very small in a typical highly-developed South Idaho project, and that it will never exceed over 1 or 2 per cent of the total area, where the project is well developed, which in- tensive development must take place if the project is to be a success. For those who have use for the data contained in the table, it is suggested that not over 1 to 2^ per cent should be added for fallow land to the waste or non-irri- gated acreage shown. The addition of a percentage for fallow land to the percentage shown in the table should give the total waste or non-irrigated area of the project. 130 REPORT OF STATE ENGINEER. Space will not permit of even a brief description of each of the sections that have been surveyed, and the readers must assume that they consist of typical, well irrigated land, planted to diversified crops. A study of the detailed table, however, should furnish considerable information in regard to each section. The 20 sections in the vicinity of Meridian consisted of holdings of various sizes, these hold- ings ranging from 4 to 19 different farms per section. The average for the entire area surveyed was 10.65 farms per section. 3 I REP OUT OF STATE ENGINEER. :BSStaSSgaStigoo-aoo,,* M wM Number 131 HHM.~ H H OOClbob 5E :JLF& WJSH.HH.H coco b en btabtNa^Jbo bb^oabsbo witooobicbscobbof-' M M M - 1 CO - M l-i to IsS l- tO CO M t* b bO b* OO CO M to IsJ to cw^tOMMOOCTooa-^cnososocflts3i>9M>-Joabacooowcn i *>-cncci>t- a* & & L CLP P 3 =ra o " r * 3 2 8 S, ST 5 tn n -^ " v><*$ jj^ ^ 3 r^- ^ S2. x* C^ rb o O* 3 132 REPORT OF STATE ENGINEER. Space will not permit of including carefully prepared maps of a sufficiently large scale to show up the individual differences that existed between the sections surveyed, nor of a table of sufficient size to show the acreages of all classes of crop that existed in each individual section. The above table gives the results secured from the survey in a rather condensed form, which, it is believed, will be de- tailed enough for all practical purposes. In working up the data, each class of crop or class of waste land was totaled separately. Of the area surveyed, which consisted of 16,065.21 acres, 4,417.22 acres, or 27.5 per cent, were de- voted to hay; grain, 4,327.56 acres, or 26.94 per cent; pasture, 2,447.58 acres, or 15.24 per cent ; potatoes, 137.19 acres, or 0.85 per cent; orchard, 2,360.4 acres, or 14.69 per cent; vineyard, 2.76 acres, or 0.02 per cent; corn, 17.26 acres, or 0.11 per cent; garden, 105.58 acres, or 0.66 per- cent; sugar beets, 155.25 acres, or 0.97 per cent; clover, 94.72 acres, or 0.59 per cent; beans, 25.14 acres, or 0.16 per cent; berries, 3.01 acres, or 0.02 per cent; peas, 198.69 acres, or 1.23 per cent; sage brush which will be irrigated, 199.62 acres, or 1.24 per cent; home grounds, 5.03 acres, or 0.03 per cent; miscellaneous irrigated crops, 273.68 acres, or 1.7 per cent, making a total irrigated acreage of 14,- 770.69 acres, or 91.94 per cent. The waste or non-irrigated acreage consisted of corrals, 99.85 acres, or 0.62 per cent; barn and stack yards, 24.78 acres, or 0.16 per cent; fence rows, 87.49 acres, or 0.55 per cent; sloughs, 44.15 acres, or 0.28 per cent; creeks, 97.33 acres, or 0.61 per cent; canal and ditch rights of way, 229.14 acres, or 1.43 per cent; county and private road rights of way, 351.19 acres, or 2.18 per cent; railroad rights of way, 93.38 acres, or 0.58 per cent; coulees, 93.10 acres, or 0.57 per cent; build- ing sites, 139.35 acres, or 0.86 per cent; high land, 2.67 acres, or 0.02 per cent; miscellaneous non-irrigated areas, 32.09 acres, or 0.2 per cent, making a total non-irrigated acreage of 1,294.52 acres, or 8.06 per cent, the total area surveyed consisting of 16,065.21 acres. The reader will bear in mind when consulting this table that all lands to which water was not applied, except uncleared land which could and will be irrigated, is listed under waste land. Consider- ing the investigation as a whole from the detailed data which are given ir^ the table, it would seem as though none of Idaho's normal projects would ultimately have REPORT OF STATE ENGINEER. 138 over 10 per cent of waste or non-irrigated land contained in them, provided the size of the projects is based on the number of acres sold and for which maintenance is an- nually paid. The data therefore seem to prove conclusive- ly that where it is desired to irrigate 100,000 acres, an ample and dependable water supply for at least 90,000 instead of only 80,000 should be secured. SEEPAGE INVESTIGATION. There has always been a serious lack of dependable data concerning the transmission losses of Idaho canals. It seems to have been customary when designing Idaho pro- jects to allow/ for a loss of one per cent per mile, based upon the amount carried at the upper end of each one-mile sec- tion. This estimate has been made rather arbitrarily and without much data to back it up, but on the whole has given fairly good results when normal soil conditions have been encountered. Idealizing that irrigation water was becom- ing more valuable each year and that projects were being continually based on narrower margins it became apparent that the transmission loss to! which a project would be subject was an extremely vital factor. It was felt that this factor was fully as important as the Duty of Water at the land or the percentage of the project that is ulti- mately irrigated, and it was decided to broaden the Duty of Water investigation by determining the seepage losses on a sufficient number of canals so that a stable basis for further estimates of these losses might be secured. It was known that the type of material through which a canal was built had an important bearing on the subject, and it was hoped through investigation to determine an aver- age loss for the different soil types and thus establish a safe basis to work from in the future. An investigation of the subject was initiated in the spring of 1912 and carried on uninterruptedly throughout that and the follow- ing irrigation season, during which time seepage losses were determined on 118 sections of different canals with a, total length of nearly 300 miles. Canal Losses. Canals are subject to three different kinds of transmis- sion losses. These are leakage, evaporation and seepage. The losses from leakage are usually caused by cheap and 134 REPORT OF STATE ENGINEER. improper construction or wornout structures, and should be practically negligible with an efficient, well-designed and carefully maintained canal. The evaporation losses from canals are usually so small as to be almost negligible. Careful mathematical deter- minations of this factor show that the evaporation losses from typical Idaho canals usually amount to not over one per cent of the total lossi to which water is subject in transmitting it from the point of diversion to the point of application to the land, 99 per cent is usually due to seep- age and only 1 per cent to evaporation from the water sur- face. That the above is true may be roughly determined very easily by any one. The evaporation from a free water surface in evaporation tanks installed for the purpose at different points well scattered throughout irrigated South Idaho averages about 1.5 inches per week throughout the irrigation season, and has never been known either at Twin Falls, Caldwell or Gooding, to exceed over 2.3 inches in any one week. A typical canal with a water surface I rod wide would have 2 acres of surface exposed per mile. A normal capacity for a canal of this width would be at least 125 cubic feet per second. A normal loss for ihis canal would be 1 per cent per mile, or 1.25 second feet, which would be equivalent to 2.5 acre feet per day, or 17.5 acre feet per week, whereas the evaporation loss from this same canal with its exposed surface of 2 acres could not average over 3 acre inches, or one-quarter of an acre foot per week. This evaporation loss, which is the highesc that could possibly take place from the surface of the cool water in the canal, would thus in the above case ainouut to only one-seventieth of the total amount lost by the canal from both seepage and evaporation. The striking compari- son that exists between the evaporation and the seepage losses that are experienced from typical canals was well brought out in the last biennial report of the Idaho State Engineer's office, and the above discussion is included here to further emphasize the very small losses that ordinary canals experience through evaporation from their exposed surface. Since the losses from leakage and evaporation are so insignificant in comparison to those experienced from seepage the losses in this report vvili all be classed as seepage losses. REPORT OF STATE ENGINEER. 135 Units Used to Express Seepage Losses. It has long been customary to express the seepage losses as per cent of the total flow lost per mile of canal, based on the flow at the upper end of each 1-mile section. This, however, is a very misleading and unsatisfactory method of expressing these losses, for they are not only largely in- dependent of the amount of water flowing in the canal, but the loss when expressed in per cent per mile shows an abnormal increase in canals of small capacity.* It will be seen that a canal carrying only a small per cent of its capacity will lose an abnormally large per cent per mile, while if the losses are expressed as so much per unit of wetted area they are bound to be less misleading and will compare favorably with the losses experienced when tht canal is full. While there are many factors which influence and affect the amount of loss by seepage, the loss is unquestionably a function of the wetted perimeter and must be expressed in terms of quantity lost per unit of wetted area if com- parable results between different canals are to be obtain- ed. For this reason all losses in this report are expressed as "cubic feet lost per twenty-four hours for each square? foot of wetted area in the canal bed" as well as in "per cent of loss per mile." Method of Measurement. Ditches or laterals carrying three second feet or less were measured with Cippoletti weirs which were carefully installed at the upper and lower ends of each section. The head on these weirs was read to the nearest .001 of a foot with small, inexpensive hook gages which were designed especially for the purpose. All of the larger laterals and canals were measured by current meters. Where conven- ient bridges could be found from wflrich to make measure- ments these were used, but wading measurements were found necessary on some of the broad shallow canals carry- ing only a small per cent of their capacity. The measure- ments of the South Side Twin Falls Main and High Line Canals were made from a boat especially fitted up for the purpose. This boat was attached to cables stretched across the canal in much the same manner as a small ferry *See Bulletin No. 126, U. S. Department of Agriculture, by Samuel Fortier. 136 REPORT OF STATE ENGINEER. boat. The North Side Twin Falls, the second largest canal included in the investigation, was rated from a car suspended on cables which were installed above and across the canal at appropriate places. The meters used in the work were the standard Gurley Price weight meters. These meters were all rated at the beginning of the 1912 season, one new one having been rated by the Bureau of Standards at Washington, D. C., and the others at the rating station of Irrigation Investigations at Berkeley, California. The 1912 rating was used for all 1912 deter- minations, and all meters were again rated at the rating station of Irrigation Investigations at Berkeley, Califor- nia, at the close of the season of 1913. Most of them showed a remarkable agreement with the 1912 rating, only one being off far enough to vitiate the results obtained. The 1913 measurements made with this meter were changed in accordance with the rating curve made up for it in the fall of 1913. The .2, .6 and .8 or three-point method of measurement was used in all cases where the water exceeded a depth of one foot, and either the .6 or integration method with shal- lower ditches. In computing the discharges the following formula was used : ( Vel. at .2)+ (2* Vel. at .6)-f (Vel. at .8) -. equals u av ge velocity The fluctuations of gage height or intermittent rise and fall of the water has been the most troublesome factor with which hydrographers have had to contend in the making of seepage measurements in the past, and it was decided to eliminate this factor as nearly as possible so that it could have no appreciable effect on the results se- cured in this investigation. It is believed that this was thoroughly accomplished, and as the method used was more or less original and has not been seen in print else- where, it will be given here with the hope that it might lx j of assistance to other engineers and hydrographers who may be called upon to make accurate determinations of the seepage losses from canals. The canals included in the investigation, and upon which seepage losses were to be determined, were looked over and examined quite thoroughly before any measure- ments were made. Rating stations were picked out and established at the head of all diversions and at intervals REPORT OF STATE ENGINEER. 137 of as near two miles apart in the main canal as sections suitable for the purpose could be found. Gages which could be read to the nearest .02 of a foot were then install- ed at each station, after which the canal was rated at each station by at least two hydrographers, each with a differ- ent meter, in order to avoid not only error in computation, but to eliminate the personal equation of the man, and any slight discrepancies in the meters. Kating curves were then plotted for each section measured using the bottom of the canal as the zero point on the curve and the point at which water stood when the ratings were made for the only other point which was determined on each curve. The water level in the canal was maintained throughout and for some time after the measurement as nearly constant as it could be, there being usually less than .05 of a foot fluc- tuation in the water level during the period covered by the investigation. After all of the stations selected had been rated by the two men, measurements were discontinued for a day and floats consisting of tightly corked bottles or tin cans were dropped into the main canal at the upper gage and allowed to float downward with the current. These floats were started at daylight, a man proceeding down with them and reading each gage in the main canal and in all of the diversions at the time that the floats passed the gage in question. More floats and another man fol- lowed the first ones at 2 or 3 hour intervals throughout the entire day and the discharge at and consequent seep- age losses between each two different points was calculated from the discharge based on the rating curves and gage heights at the time that the floats passed the different stations. Determinations by the above method compare discharges of practically the same flow or wave of water at the time it passed different points, and is believed to be far more accurate than any simultaneous measurements. While the floats did not necessarily proceed down the canals at exactly the same rate as the average velocity of the ditch, and while the rating curves, each of which were based on but two points, may not have been absolutely accurate, the canals were held as uniform as possible, and as there was biit slight fluctuation in any case between the time of the original rating and the time the floats passed the gages it is believed that the discharges secured from the curves are 138 REPORT OF STATE ENGINEER. quite accurate and that the results, secured as above out- lined, have eliminated personal equations of men, individ- ual characteristics of meters, and slight fluctuations of canals and are more accurate on the whole and better than any other method that has yet been devised. The table which follows the descriptions given below gives the aver- age seepage loss for a 12 or 14 hour period of the different sections of each canal that have been investigated. It is regretted that space will permit of only a very brief de- scription of the canals included in the investigation. They are all more or less typical of the ordinary canals in use throughout the West and it is hoped that the following brief description will furnish sufficient data to give a fair- ly accurate idea of the different sections included in the investigation. The numbers of the following paragraphs correspond with the numbers of the different sections in the seepage table, and are arranged in practically the same order. 1 to 21 inclusive. Typical small farm laterals located on the South Side Twin Falls Project, Salmon River Project and the Ridenbaugh Canal in the Boise Valley. The majority of the soils through which these laterals were constructed consisted of the medium clay kam or lava ash common to South Idaho. The n^ajority of these soils were underlaid with calcareous hard pan at depths ranging from one and one-half to four feet. Some of these laterals had rather swift velocities, erosion having takeo place down to the hard pan. 22. This section was located five and one-half miles southwest of Rigby in the Upper Snake River Valley and was constructed through a gravelly sandy loam soil. 23. A typical farm lateral on the South Side Twin Falls Project. 24. A lateral of the Salmon River Project near Am- sterdam. The abnormal amount of seepage from this lat< eral was caused by the shallow soil through which it was constructed, there having been a large amount of shale incorporated into its banks. 25 to 28 inclusive. Typical laterals on the South Side Twin Falls and Salmon River Projects. 29. Typical lateral on the Portneuf Marsh Valley Project near Downey. REPOET OP STATE ENGINEER. 139 30 to 33 inclusive. Typical laterals of the Oakley Project. 34 and 35. Laterals near Rigby; constructed through very gravelly soil. 36 and 37. Laterals near Hollister. Clay loam soil. 38 to 40 inclusive. Laterals of the Oakley Project. 41. Lateral near Rigby; constructed through very gravelly soil. 42. Typical lateral, Salmon River Project. 43 to 45 inclusive. Typical laterals, Oakley Project. 46. Lateral of the Burgess Canal near Kigby; con- structed through a medium gravelly soil. 47. Typical lateral of Portneuf Marsh Valley Project mear Downey. 48 to 51 inclusive. Typical laterals of North Side Twin Falls, South Side Twin Falls and Oakley Projects. Sec- tion 50 showed a gain occasioned by porous irrigated land above the canal. 52. Lateral of Burgess Canal near Rigby; constructed through gravelly soil. 53. Typical lateral of South Side Twin Falls Project. 54 and 55. Main Canal of Murphy Land & Irrigation Co., constructed through medium clay loam soil, section 55 containing a few somewhat gravelly side hill sections. 56. Extension of East Side Main Canal, Oakley Project; constructed through heavy clay loam soil slightly mixed with sand; heavy grade with consequent swift velocity. 57. Lateral of Twin Falls North Side Project rear Wendell. 58. Lateral C, Portneuf Marsh Valley Irrigation Project, 2 miles north of Downey. 59. Portion of Main Canal, Twin Falls Salmon River Project. 60. Portion of Vance Canal four and one-half miles southwest of Rigby. Soil very gravelly. 61. Section of Main Canal of the Twin Falls Salmon River Project, commonly known as "Main 2 V Canal, carrying only a small per cent of its capacity. 62 to 64 inclusive. Parts of Main Canal, Portueuf Marsh Valley Project. 65. West Main Canal, Oakley Project. First season of use; was constructed around a very gravelly hillside; 140 BBPOKT OF STATE ENGINEER. Lower bank showed much gravel but contained sufficient percentage of clay to render it comparatively impervious. 66 and 68. Main Canal, Portneuf Marsh Valley Project. 67. Lateral 21 of Salmon River Project. Bather shal- low clay loam soil with banks solid and compact. 69. Typical lateral of South Side Twin Falls Project. 70. Portion of Main (Janal of Salmon River Project near Hollister, carrying only a small per cent of its capacity. 71. West Main Canal, Oakley Project. Canal was con- structed through a gravelly side hill formation which had n sufficient amount of clay mixed with it to render it com- paratively impervious. 72 and 74. Typical laterals of South Side Twin Falls Project. 73. Lateral A of Salmon River Project, carrying only a small per cent of its capacity. 75, 83, 87, 89, 98, and 100. Main Canal of Pioneer Irri- gation District in the Boise Valley. Section 75 of this canal was located between Caldwell and Nampa and traversed a territory where ground water was very close to the surface. The gain in this section was due to the proximity of the ground Avater. The remainder of this canal was fairly typical of Idaho canals, having been con- structed almost entirely through a clay loam soil of a me- dium nature. 76 and 77. East Side Main Canal, Oakley Project. 78 and 79. Portions of Main Canal, Twin Falls Salmon River Project. 80. Randall Canal near Rigby; constructed through gravelly soil. 81 and 82. Main Canal of Deitrich segregation, Idaho Irrigation Company's Project near Richfield. Section 81 was constructed in the main through clay loam s^il but contained several rock cuts. 84. Consisted of the entire length of Perrine Coulee, the well-known lateral on the South Side Twin Fails Project. This coulee was measured during the month of July, 1913, at the height of the irrigation season. Measure- ment of this coulee was, made at this time to determine whether or not well defined coulees picked up enough waste water from the adjacent farms to more than offset REPORT OF STATE ENGINEER. 141 their seepage losses. Extreme care was used in the Meas- urement of this coulee and it was found that the waste water which was picked up hardly equaled or offset the loss in the coulee by seepage, the net loss being .1 of cne per cent per mile. The section of the coulee was so irregu- lar that there was no attempt made to base the seepage losses on the amount of wetted area in the coulee. 85 and 86. Portions of Main Canal, Twin Falls^almon River Project. Section 86, first section below lIR^Jieck basin, listed as 99 and 101. 88 and 90 to 95 inclusive. Farmers' Co-operative Canal in the Payette Valley near Emmett. Tt had been thought by some that this canal had abnormal losses and that the seepage conditions in the valley were largely due to the losses from this canal. The losses from the canal, as will be seen from the table, were rather low. One section, where ground water was near the surface in the surround- ing soil, showd a gain. The measurements as a whole clearly indicate that the seepage conditions in the Payette Valley are not caused by the seepage losses from this canal. Soil, a clay loam and sandy loam. 99 and 101. The check basin in the Main Canal of the Salmon Eiver Project. These two sections represent meas- urements of this check basin during the different years. Re- sults represented by No. 99 were secured during the season of 1912, and those represented by No. 101 were secured during July of 1913. This check basin is simply an en- largement of the canal or a pot hole which is used MS part of the canal section to eliminate the necessity of con- structing a canal around it. The check basin covers about 62 acres when full. The soil in the bottom of the basin is a clay loam varying in depth from one to two feet, under laid by lava rock. The measurements clearly indicate that it would be wise to construct a canal around this depres- sion. 102 to 106 inclusive. Include the High Line Canal of the South Side Twin Falls Project from the point where it leaves the Main Canal to Cottonwood Flumo south of Kim- berly. This canal shows a gain in two different sections. Section No. 102 is that portion which crosses McMnllin Creek, and section 104 is that portion which crosses Rock Creek, there being porous irrigated land lying above each 142 REPORT OF STATE ENGINEER. one of these sections. The gain clearly indicates that the canal in these sections is picking np from sub-surface sources some of the underground water from the porous irrigated land above. 107 to 112 inclusive. Represents results secured from different sections of the Main Canal of the North Side Twin Falls Project from Milner to Jerome Reservoir. The Upper end of Section 112 is located at the Milner Dam, and the lower end of Section 107 includes part of Jerome Reservoir. Part of Section 112 is lined with concrete. Section 111 includes Wilson Lake Reservoir. 113 to 118 inclusive. Includes the Main Canal of the Twin Falls South Side Project from Milner to the point approximately 25 miles below where the Main Canal di- vides into the High and Low Line Canals. Section 1.16 includes Dry Creek Reservoir only. This reservoir is formed where the main canal crosses Dry Creek, where the canal simply consists of a lower bank, the water back- ing np Dry Creek far enough so that it forms a lake cov- ering 965 acres. The embankment is approximately one mile long and 35 feet high. No. 118 is that portion of the canal extending from the wagon bridge near Milner and immediately below the dam to a point 3.35 miles below. There are several rock cuts throughout this section, it be- ing the only section where an abnormal loss occurred. The losses in all other sections were practically normal, yet tho canal lost over 500 cubic feet per second throughout the section observed, which was less than 25 miles in length. When considered from the standpoint of the total amount of loss alone, leaving out of consideration the percentage, this loss is thorouprhlv enormous. The South Side Twin Falls Canal is constructed princi- pally through a clay loam soil of a rather impervious na- ture and was running very full of water at the time of tho investigation. REPORT OF STATE ENGINEER. 143 UOT1D9S H[ 10 1391 DUOD9S HO1JD9S JO pub jgddn UOUD9SSSOJD 11 00COWCao^Mi^^rH05MNt^U5l^lfleOOCt^l^0OWOCOOU3N05aia)a)4iQ)aja)a>aja>a)ii)^ 144 REPORT OF STATE ENGINEER. Q) > cJ c3 o o Him .i.xl SSOJ JU33 J9"5"^"e^5"^ : ^"^"o^^ r =^^ ; TOI J9d SS01 JTfOt-CXOOCCXOC^OCOCCT ' rH COi-to oo '2 <=>o S5? ( 55 O000 ' I9ai puonas looooocooooo c ^oooo < omoooo | oooooooo(oocoo< pua J3A\Ol J93J PUOD9S UOIJD9S |O pua J9ddn c- oo w'o os as cs N c 1 co eo t t os en OT puooas J9d ' 19aj ajtiubs UOT1D9S SSOJD J 'JHS J91UA1 jo qjpiM -Ay 199 J jo qidap - o * c -fl- 1 i-HCCCIC
  • w oo oo o> CD D o ao oc ao ta i - oo oo ooo oo REPORT OF STATE ENGINEER. I I o o o G & G G a *> o o fill Lf5 IM r-) . 3 C i o us Tt ?o IH TH oo o L N oo in < C C QJ 'M "53 K cS cs n PQ fe d o ei.c X cd cc o y Oo uo o & 3~^0 "l>~30~?-r U5 (M tXJ C-000 145 I & * 5 . S- O Q tf IM I THCq THOlH T" '"'i ; ; ; ! i ; fH O5 t oo M CvJ IO O CQ O OO < TH'CO, l iH CO . i I - "7itj3C*-OCO'*Jl>-'*fOOOTt t OOC>< O 1C O O5 Utl ( ICq(M(M(M(MTHeOTHTH(M rH iH OO y) g^(M s in which the irrigatorp desired to go back to the old continuous flow system of delivery. 154: REPORT OF STATE ENGINEER. 6- Preparation of the Land. An even application of irrigation water to all parts of a field cannot be secured with rough, uneven, or improper ly leveled land. It is therefore apparent that a maximum crop cannot be secured on land that is rough and improp- erly leveled. The value of. proper leveling and the effect of improper preparation on the Duty of Water is so evi- dent that they will not be discussed in this report. Neither will space permit of an extended discussion on the proper methods of preparing land. Generally speaking the land should be so leveled that uniform application and penetration of the Avater can be secured. In order to obtain the above water should never be flooded too far between cross ditches. Prom 300 to (100 feet, depending upon the porosity and topography of che land, is usually about the right distance. 7. Kind of Crop. The kind of crop, whether cultivated or uncultivated and the length of season that it requires water, have a very direct bearing upon the amount required. Alfalfa requires water from early spring until late fall, as do the clovers and pasture grasses, and has been found to require nearly twice as much water during the irrigation season as the spring or winter grains, which require it for but a comparatively short season. Alfalfa has shown a de cided tendency throughout the investigation to produce the most crop where the most water has been applied. It has been made plain that water should never be left stand ing on alfalfa more than an hour or two if the best results are to be obtained. No more should be applied at an ir- rigation than the soil will readily absorb. Where the above method of irrigating alfalfa is followed it has been found almost impossible to reduce the yield by applying too much water. The yield produced, however, is in but few cases proportional to the amount of water applied, and it is doubted whether or not it will ever be found feasible to ap- ply more than 3 acre feet per acre to alfalfa or pasture on the medium clay loam soils. The investigation has proven that grains and potatoes can very easily be over-irrigated. Where abnormal amounts have been applied to grains the yields have always been materially reduced. By far the larger number of the experiments included in the investigation have been REPORT OF STATE ENGINEER. 155 carried on with the spring and winter grains, and these have proven that there is no doubt but that it will rarely be profitable to apply more than one and one-half acre feet per acre to grains. The above applies to the medium or clay loani soils only. Where grains are planted on fertile soils less than the above amount may be required. Where as much as 3 acre feet per acre have ben applied to spring grains at the Gooding Experiment Station the yields have been repeatedly reduced to that which was produced on adjoining plots where no irrigation water was applied, while the maximum yield was produced with ap proximately one and one-half acre feet per acre. A cultivated crop such as corn, garden or orchard that can be cultivated between the rows will require, all other things being equal, considerably less water than an un- cultivated crop on account of the decreased evaporation losses induced by the cultivation. The experiment on the Dunlap orchard, which was car- ried on during the years of 1911, 1912, and 1913, near Twin Palls, is striking proof of the great saving of moisture that can be made by properly cultivating the surface soil. This orchard was thoroughly clean cultivated and made to all appearances a maximum growth and crop of fruit, yet it received only a total of approximately 0.75 acre feet per acre during the three seasons, 1911 to 1913 inclusive. This experiment was carefully conducted and shows con- clusively that the methods used by the Southern California walnut, orange, and lemon growers for the conservation of moisture by thorough surface cultivation will be very effective if carried out in Idaho, and that orchards, if planted on a deep soil of medium texture, will require very small amounts of irrigation water for at least the first 10 years of their growth. The Dunlap orchard was seven years old and produced 300 boxes of excellent fruit per acre during the last year of the experiment, with a total application of 0.75 of an acre foot per acre in three years, with an average annual rainfall of approximately 12 in- ches. This performance seems to prove that this orchard, no matter what its age, will never require more than 1.5 acre feet per acre during any one season, no matter how large a crop of fruit it can be made to produce. This ex periment, and many others included in the Investigation* strongly emphasize the value of surface cultivation as a saving of water. Where clover or alfalfa is planted as a 156 REPORT OF STATE ENGINEER. cover crop orchards will require at least as much water as alfalfa when grown for hay. 8. Fall Plowing. Fall plowing should always be recommended. It loosens up the soil early in the fall and renders it more capable of absorbing winter rains and reduces the run off. The use of fall plowing benefits the soil and irrigator in many ways. The fact that the land is plowed in the fall and ready for crop as soon as it has dried out sufficiently in the spring enables the farmer to plant his crops early and in due time, which he might have been unable to do if the land had to be spring plowed. Fall plowing thus allows the crop to start off early in the spring and permits it to make better use of the winter precipitation, and a greater yield with a less than normal quantity of water is usually secured. The turning up and loosening of the soil in the fall is also a decided advantage, for the extra freezing and thawing that takes place together with the aeration of the soil, sets free an added amount of plant food and makes a larger yield possible, all other things being uniform. An experiment was carried on at the Gooding Experi ment Station during the season of 1911 to determine the effect of fall vs. spring plowing on the Duty of Water and yield produced with the results which are shown in the following table. A study of the table makes it apparent that too much emphasis cannot be placed on the many ad vantages of fall plowing. Results of Fall versus Spring Plowing Experiment, Gooding Experiment Station. Yield of grain <* ^ c O ^ +J ^VM ?0 * Treatment of sub-plot 5Si. Per Per *= acre '53 S- c ub^ 5* Q* acre foot i Feet l 2 .314 .315 Fall plowed minimum irrigation Spring plowed minimum irrigation .376 .376 41.18 32.88 109.5 87. 5 38.0 38.0 3 4 .314 .314 Fall plowed average irrigation Spring plowed average irrigation .962 .962 43.65 39 77 45.5 41 4 41.0 41 5 6 .304 .305 Fall plowed maximum irrigation 1 533 1.533 47.54 45.26 31.0 29.5 42.0 42.0 Spring plowed maximum irrigation OTHER FACTORS WHICH HAVE A BEARING ON DUTY OF WATER AND IRRIGATION IN GEN- ERAL. Length of Season. The length of the irrigation season is in many cases fixed REPORT OF STATE ENGINEER. 157 by statute, but the true length of the season or the length of time that crops- actually require water is a much mooted question. Many canals are required to run water through out practically the entire year for domestic purposes and stock water, but the number of days that such canals run water, or the amount of water they divert at such times does not furnish an accurate idea of the water require- ments of the crops under them. The Duty of Water In- vestigation, as carried on, however, throw's much new light upon this subject, for in the main only the amounts ac tually applied to the crops have been considered. In order to furnish a sound basis in regard to the proper length of the irrigation season under average South Idaho condi- tions, the number of days that elapsed between the date of beginning the first irrigation and the end of the last irri- gation of the season of all of the individual tracts in- cluded in this investigation is shown in the following table. There has been nothing added either at the be- ginning or end of the irrigation season for stock water, and the table should be found very dependable as the totals given show the true length of the season that crops require water under Idaho conditions. Table Showing Average Length of Irrigation Season of Plots Included in the Four Years' Duty of Water Investigation. to o , *>i ^c Crop ~- ce u & T'C'3 rt - o Sfl| 1* rt o " U u bo.^f 0) O *i .w I* |1I > _!} U Grains 1910 76 3.6 3 46.0 Alfalfa and Clover. . 1910 27 4.7 95.4 Grains 1911 % 2.1 17 35.5 Alfalfa and Clover... 1911 34 6.1 1 111.4 Grains 1912 60 3.7 10 39.7 Alfalfa and Clover... 1912 25 5.6 87.3 Grains 1913 66 3.1 8 48.9 Alfalfa and Clover . . . 1913 15 5.1 96.5 Maximum J length of ! irrigation season, days Average dates of irrigation First irriga- tion Last irriga- tion 87 144 May 27 May 12 July 16 Aug. 12 64 % 142 June 13 May 14 July 19 Sept. 2 61 123 June 9 May 23 July 18 Aug. 18 110 119 June 5 May 16 July 23 Aug. 20 *Exclsive of plots having- one irrigation only. Proper Amount to Apply per Irrigation. A study of the tables included in this re]H>rt shows that the amounts that have been applied to the various tracts per irrigation have varied widely. It is not uncommon to find soils that are so impervious that they will barely ab isorb 0.1 to 0.15 feet in depth per irrigation, on the one hand, or soils so porous that they can be made to absorb 158 REPORT OF STATE ENGINEER. from 1 to 3 feet in depth per irrigation on the other hand. The investigation has made it plain that from 0.1 to 0.2 feet per irrigation is rather insufficient if economy of water is desired, for the moisture forced into the soil does not last long enough between irrigations, thus necessitat ing more irrigations per season. As an unavoidable loss from evaporation always occurs at each irrigation it is desirable to apply as few irrigations during the season as will be required to maintain a sufficiently high moist- ure content in the soil for good plant growth. Impervious soil can usually be improved by the addition of manure or the plowing under of alfalfa which incorporates more humus into the soil and changes its nature, after which it will not only absorb water more readily but will retain it longer. It is a singular coincidence that the same pro cess which renders imperviousi soils more porous, also rend- ers porous soils more impervious, for the addition of hu- mus, either decomposed or otherwise, tends to fill up the ex- cessive amount of pore spaces and renders this soil less porous. The results of the investigation indicate that, generally speaking, from 3 to 6 acre inches per application is the correct amount to apply, and that impervious soils should he so manipulated that they can be made to absorb at least the lesser amount, while the porous soils should be so handled by using large irrigation heads that they can be irrigated with not over 6 acre inches per application if economy of water is desired. The fact that a head of one cubic foot per second delivers almost exactly one acre inch per hour makes it compara- tively easy for an irrigator to determine approximately how much water he is applying to his land without any difficult mathematical calculation. It is hardly consid- ered that it will ever be practical to predetermine just how much should be applied per irrigation, and then to apply this amount, no more, but it is believed that intelli- gent and economical practice demand an approximate knowledge of the amount that is being applied. LOSSES AND WASTE OF WATER. The individual irrigator is most concerned with the losses or waste of water that may be experienced from four principal sources: (1) transmission losses. (2) evaporation losses, (3) surface waste, (4) deep percola- tion waste. REPORT OF STATE ENGINEER. 159 Transmission Losses. Those losses are sometimes far greater than most irri- gators realize. The seepage data contained in this report clearly show that the transmission losses of an irrigation project between the point of diversion in the stream and the point where it is delivered to the farmer may range from 10 to as high as 50 per cent. Where storage reser voirs are included as part of a project the losses experi- enced before it is delivered to the farmer may be still greater and total as much as 75 per cent of the amount diverted. The irrigator himself is usually most concerned with the transmission loss in his own individual supply ditch which carries the water from the point of delivery to the land. These supply ditches usually average from one-quarter to one-half mile in length and where one sec ond foot or less is carried the losses in them may amount to as much as 20 to 30 per cent per mile, but 10 per cent per mile would be a fair average for the medium soils. The data included in this report emphasize the desirability of short canals, and that even these should be well con structed through material of a rather impervious nature Evaporation Losses. Of evaporation losses those from the irrigated fields are the ones which principally concern the irrigator. These are more or less of a constant and represent a loss that is rather hard to overcome, for the majority of the evap oration losses from the fields take place within 48 hours after irrigation water is applied and before cultivation of the surface to reduce the losses can take place. Supple- mentary investigations of evaporation loss at the Good ing and Twin Falls Experiment Stations .show that where 2 acre feet per acre is used during the season, the same having been applied in from four to six equal irrigations, from six to nine acre inches of it are almost invariably evaporated into the atmosphere, without having transpired through the plants. The high and almost unavoidable loss from evaporation, a large portion of which takes place within three days after application, emphasizes the desir- ability of applying as few irrigations as possible. Inves- tigations* made by the Irrigation Investigations Depart- ment sihow that the evaporation loss from soils may be ma- terially reduced, (1) by applying the water in rather deep furrows, and (2) by the maintenance of an efficient dust mulch on the surface. This, of course, will apply more r^f TTU--^v.4.nv>+ QtlfiVinc, 13 nil At? *> XTrt A C 160 REPORT OP STATE ENGINEER. particularly to orchards and other clean cultivated crops. The water requirements of alfalfa fields can be materially reduced by disking in the late fall or early spring. This manufactures a sort of loose non-conducting layer on the surface and thereby decreases evaporation, and at the same time renders the surface so much looser that it will absorb more of the moisture which is received through natural precipitation. Surface Waste. Many theoretical irrigatorsiorthose unfamiliar with Idaho conditions maintain that the farmers should so prepare their fields and so handle their water that no surface waste be allowed to run off. This, however, is not feasible in Idaho at the present time if the value of labor, land, water and crops produced be taken into consideration, and an average irrigator is surely justified in allowing a small per cent of waste providing the same cannot be economically prevented. It is believed that the average waste that has taken place from the individual fields included in this in- vestigation are fair and normal, and that they approxi- mately equal those that may be expected in average irriga- tion practice in this State. The following table has been compiled in order to show the average waste that has taken place from the tracts included in the investigation, the per- centages given being based on quantity of water delivered to the land. Percentage Wasted of Total Amount Applied. Crop Class of soil Number of irrigations Percentage of waste Maximum Minimum Average Alfalfa Grain Alfalfa Grain Clay loam Clay loam 302 291 147 122 55.7 83.3 24.8 31.4 0.0 0.0 0.0 0.0 19 1 25.3 1.8 2-3 Gravelly Gravelly This table gives the average waste from several hundred of the individual tracts that were included in the Duty of Water investigation during the 4 years, the soils and crops being divided into two classes for convenience and ready comparison. The table shows that over one-half of the water applied to grain and alfalfa on clay loam soils is sometimes wasted, and that the average amount wasted of the total amount applied was 25.3 per cent for grain and 19.1 per cent for alfalfa. While the above percentage REPORT OF STATE ENGINEER. 161 of waste may seem high to many, the results of the in vestigation have shown them to be a fair average. The above figures, however, are based on the result from single fields, and irrigators should not be allowed to waste this percentage from their entire holdings. Their irrigation sys- tems should be so laid out that as much as possible of the waste water could be caught up and used over again on one or 11101-0 fields before it is; finally allowed to be wasted off the farm. It is safe to assume that the average farms of Idaho could be so laid out that waste would not run directly off of the farm from over one-quarter its area. Rather steep farms of small area would naturally waste more water, all other conditions being uniform, than the large flat farms with the more porous soil. Under nor mal Idaho conditions, however, it is believed that all water contracts should provide for a sufficient delivery over and above the actual water requirements of the soils and crops so that the irrigator might be allowed to waste a small amount, probably between seven and one-half and twelve and one-half per cent of the amount delivered to him, and still retain sufficient for his crop needs. This is not a very serious factor when a whole project is taken into consideration and no large allowance would have to be miade for it, for a large amount of all of the waste water can usually be caught up by the lower laterals and used over again. A larger amount of the waste could be caught up and reused on the larger projects than could be done on the smaller projects. This factor is one that must not be overlooked when designing irrigation projects. All measurements tabulated in this report, with but few ex- ceptions, are those of the actual amounts retained upon the fields in question, and if these measurements are used in alloting water to a new project care must be used to make a reasonable allowance for the unavoidable waste that each individual farmer's water is subject to. Deep Percolation Loss. The abnormal amounts that were applied to some of the tracts included in the investigation indicated even as early as the first year of the investigation that the losses from deep percolation were far greater than most irrigators realize. This seemed true, for it hardly seemed possible that alfalfa or other crops could utilize and transpire any more water on porous soils that was required for the same production of the same crop on the medium soils. The 162 REPORT OF STATE ENGINEER. rapid rise of the water in wells during the irrigation sea- son in the near proximity of the lands irrigated demon- strated that such large losses were taking place from this source that it was decided to conduct a simple tank ex periment in order to show just what these losses amounted to and whether or not the crops themselves on the porous soils actually required any more water than those planted on the impervious soils. A tank 2 feet in diameter and 6 feet deep was construct od and installed in the gravelly soil adjacent to one of the experimental plots on the Bate farm in the vicinity of Bigby. This tank was buried in the soil in an upright position with the top flush with the surface and was care fully filled with soil in as near its normal and original position as the same could be placed. The tank was water tight with the exception of one place in the bottom which terminated in a three-quarter inch galvanized iron pipe which led to a tub in a curbed pit several feet away. Al- falfa was planted on the tank and the tank was irrigated during one entire season by applying the same amount to it that was applied to the experimental tract and also to the farmer himself. Seven irrigations, totaling 6.6 feet in depth, were applied to the experimental tract and also to the tank. The alfalfa rew luxuriantly throughout the sea- son, showing that sufficient moisture was retained in the 6 feet of soil of the tank and an equivalent of a depth of 5.5 feet, or 83.5 per cent of the total amount applied, was caught in the tub in the curbed pit, having precolated from the tank. Mathematical calculation showed that the tank retained an average of only approximately .15 feet in depth at each irrigation. The experiment was continued during the fol lowing year, that of 1912, by irrigating the alfalfa in the tank every time it needed water with .15 feet in depth per irrigation. It was) found that ten irrigations were required during the season, representing a total application to the tank of 1.5 feet, there having been only a small trace of percolation from it. The alfalfa grew luxuriantly through the season, was cut, thoroughly cured and weighed, and it was found that the hay which grew upon the tank yield- ed at the rate of 7.15 tons per acre, which proved quite conclusively that the soil in the tank had sufficient irri- gation for the production of a profitable crop. REPORT OF STATE ENGINEER. 163 Tn view of the above and other observations throughout the investigatin there is no doubt in the mind of the author but that an application of 6 acre inches per irrigation to the most porous of soils, which is probably the least amount that can be evenly applied under present practice, will last fully as long between irrigations and grow just ;is much crop a.s if from one to two acre feet per irriga- tion are applied. The only known practical means of ir rigating porous soils so as to eliminate as much as pos- sible of the needless* deep percolation loss is to prepare these lands for irrigation with the border system into rather nar row lands of reasonable length, say not over 40 feet wide and 300 feet long, and irrigate them with large irrigation heads of from 5 to 10 second feet. On all but the most porous of land this type of a system and size of irrigation head will successfully and economically irrigate the lands with an average application of not over 6 acre inches per irrigation. From the above discussion of the losses and wastes to which irrigation water is subject it will be seen that in abnormal cases where a large amount of transmission loss, evaporation loss, surface waste and deep percolation waste are experienced, only a very small amount of the Avater diverted, and probably not over 10 per cent, can be used beneficially by the plants. It is very probable that even with the very best of conditions not over 40 per cent of the water actually diverted from a river or source of supply is, or can be, used beneficially by the plants. The above discussions are given so much in detail with the hope that they will demonstrate to the reader that the amount of loss to which water is subject, rather than the actual requirements of the crops, are the real factors which have fixed the water requirements of a project in the past, und with the idea that they will furnish information by means of which the abnormal losses that are not being ex- perienced in some localities can be reduced. EFFECT OF LENGTH OF RUN ON DUTY OF WATER. Water should never be flooded too far or be run in cor vugations of too great a length between cross ditches on juiy class of soil. Where water is run too far between cross ditches even application is not obtained. Too much is usu- ally absorbed on the upper end of the field near the supply 164 REPORT OF STATE ENGINEER. ditch, or too little at the lower end near the waste ditch This is particularly true with coarse porous soils, there usually being an abnormal amount of deep percolation Avaste experienced if water is left run long enough to thor- oughly irrigate the lower end of the fields. It is concluded from a study of the results secured in the entire investi gation that it is never feasible to run water between cross ditches a greater distance than from 300 to 600 feet, de pending upon the nature of the crop, the topography of the land, the size of irrigation head used, and the porosity of the soil. A series of experiments were conducted on the porous soils in the vicinity of Kigby for the determina- tion of the effect of length of run upon the amount required per irrigation. It was found that an application of from four to 1 nine acre inches per irrigation lasted fully as long between irrigations and gave equal results with the larger applications, and that the farther water was flooded the greater the amount that was required per application. The soils under consideration were very porous and gravelly and the following curve, based on the results secured from 20 different plots of varying lengths, shows very conclu sively that the amount required per irrigation and per sea son increases very rapidly as the length of the run is in- creased. These plots were irrigated with heads of from y es*?//j o/ /% CURVE SHOWING EFFECT OF LENGTH OF RUN UPON DUTY OF WATER. REPORT OF STATE ENGINEER. 165 3 to 5 second feet, and were only fairly well prepared for irrigation. EFFECT OF TOPOGRAPHY ON DUTY OF WATER. It has been found, all other things being equal, that while steep slopes and rough topography in general affect the amount that must be delivered to the individuals who fire farming the land, the crops grown on the rough or steep land do not actually require any more moisture than where grown on level land. A larger amount of waste water is unavoidable, however, where steep slopes are irri gated, and a consequent greater amount must be delivered to the irrigators where these lands exist. Poorly prepared land absorbs somewhat more water than where well pre pared, for the low spots become over saturated if water is held on lon- enough to wet up the high spots. The great- er portion of the amount that is wasted from the lands over and above the amount retained, if the system is well de signed, can usually be caught up and measured out to oth er customers, in which case a project as a whole will re- quire but little more water if the lands are steep but well prepared than it would if the farms had only a small 01 medium slope. EFFECT OF SIZE OF IRRIGATION HEAD. Where the individual irrigators are able to command irrigation heads of rather large size, from two to ten sec- ond feet, their actual requirements in acre feet per acre per season are usually materially reduced over the require- ments where the small but continuous flow allotments are used. The effect of a large irrigation head is practically opposite to that of a long run between cross ditches. The larger the head used or the shorter the distance betweeen cross ditches, the less the net water requirements willbedur- ing the season. The ability to command a large irrigation head has many advantages, the principal ones among them being the saving of water and time that are required for irrigation. The savings that are effected by the use of large heads are more material where porous soils exist, for the lands can be flooded so quickly that abnormal losses from deep percolation are eliminated. The ability to com- mand large irrigation heads usually necessitates a rota- tion system, where the water is used not to exceed from 166 REPORT OF STATE ENGINEER. one-fourth to one-tenth of the time on any one farm. This allows plenty of opportunity for other necessary farm work and permits the irrigator to give his undivided attention to the irrigation water while the same is available, which careful attention in itself invariably results in a material saving of water. The value of an efficient system of rota- tion and the ability to command a comparatively large head of water cannot be overestimated. Rotation systems however, in order to be of the greatest possible value, should be somewhat flexible. Few farmers under the same project, or even under the same lateral, have the same types of soil, the same crop, or even the same areas, and the systems of rotation that seem to give the best satisfac- tion are usually those where a continuous flow is main tained in the main laterals and the farmers under each lateral are allowed to work out the rotation system best adapted to their individual needs. The kinds of crop should determine the interval between irrigations, and each user should be allowed to control the entire flow of the lateral ai intervals of from 10 to 14 days, the length of time he is allowed to retain water at each interval being dependent upon the number of acres owned. EFFECT OF INDIFFERENCE OF WATER USERS. There are many factors which have a decided influence upon the Duty of Water, but in actual practice the value of the irrigation water may have a greater inflence than all other factors together. Where water is very valuable and is settled for on a basis of a certain rate per acre foot by the person who uses it, a very high Duty is iiivariabty secured, no matter what may be the climate, the class of soil or the crop grown. Under the above conditions all irrigators soon become skillful. Continuous flow allot- ments which are paid for on a flat basis per acre for the sea- son are the greatest enemy to a high Duty of Water. There are but few other commodities that are delivered to the consumers on this basis, and irrigation water should not be, for the flat rate of payment, independent of the amount used, places a premium on carelessness and waste. With- out a strong underlying incentive to save water a high Duty can never be secured on any project. It is believed that the acre foot should be made the unit of measurement and the basis of all contracts and decrees, and that the REPORT OF STATE ENGINEER. 167 annual maintenance of all projects should be based upon the acre feet actually used during the season by the in- dividuals. It is believed that the adoption of the acre foot as a basis of all water rights and the sale or delivery of water by the acre foot would go further toward increasing the Duty without decreasing crop production than any other feature that could be inaugurated at this time. EFFECT OF CONTINUOUS FLOW ALLOTMENTS. The effect of continuous flow allotments is also to place a, premium upon waste and the careless use of water. There is no doubt but that water contracts calling for a uniform continuous flow are radically and fundamentally wrong. No matter how much a user may waste one day lie is entitled to and sure of the same amount the follow- ing and succeeding days. The adoption of a quantity basis such as a Duty expressed in acre feet per acre would not jeopardize old water contracts or priorities, for the water right holders could be allowed quantities equivalent to the continuous flow to which they are now entitled. Tf water was distributed on a quantity basis, measuring de- vices would be installed and the water would not be per- mitted to run to waste between irrigations as is usual where the uniform continuous flow method of delivery is in vogue. The users would fear lest their season's allot- ment be exhausted before the end of the season and would inaugurate rotation systems, which in themselves would increase the Duty very materially. They would then call for only enough water for the sufficient irrigation of their crops each time, after which it would be to their own in- terest to see that the headgate be shut down and that none be let run to waste between irrigations. The adoption of such a system as above outlined would work out to the best advantage with storage systems. EFFECT OF TIME OF APPLICATION. The stage of growth at which irrigation water is ap- plied, particularly with the grains, is found to have almost as much effect on the crop produced as the total amount of water applied. It has been found that one good irri- gation at a critical period of the plant's growth is worth as much as two or three at other stages of its growth. The time of irrigation does not seem to have so much effect 168 REPORT OF STATE ENGINEER. upon alfalfa and clover. The effect of time of application upon the yield of grain produced has been eliminated from the present investigation as maich as possible by applying irrigations on the comparable plots at as near the same time as possible. This factor has been shown to be so important that a Federal Experiment Station has been started at Twin Falls for the sole and specific purpose of determining at which stage of groAvth the various crops should be irrigated in order to give the best results. The investigation as a whole, however, has thrown considerable light on this subject. In a general way it seems best to irrigate alfalfa and clover before and after each cutting, and as near be- fore the time of cutting as will allow the surface soil time to dry out sufficient for the cutting and curing of the crop. Alfalfa, throughout the investigation, has been in- clined to produce the most crop where the most water was applied, and it seems best to keep a medium but uniform content of moisture in the soil of an alfalfa field through- out the irrigation season. Only as much as will be promptly absorbed, however, should be applied, for water should never be allowed to stand on alfalfa for any length of time. With the grains the maximum amount of water seems to be required at the booting, jointing, and soft dough stages in order to properly fill the kernels. Grain should never be allowed to suffer for water during the blooming or soft dough stages, or shriveled grain will re- sult. Potatoes seem to require a medium but uniform moisture content in the soil from the time the plants ap- pear above ground until just before maturity, when the water should be turned off in order that the tubers may ripen properly. Potatoes require practically the same amount of moisture as grains, which is to all intents and purposes about one-half the amount that is required by alfalfa, clover, and pasture, on the same soil. Potatoes should never be allowed to dry out until maturity nor should they be flooded, for the soil around the tubers in the hills should never be saturated. They should be irri- gated with a rather deep furrow between the rows, in which case only a sufficient amount for good growth will reach the tubei-s through capillary attraction. Pastures require light but frequent applications of water and should never be allowed to dry out or suffer for lack of water if a maximum yield is to be secured. Orchards require but REPORT OF STATE ENGINEER. 169 little water during the early part of the season if the soil is thoroughly cultivated. Bearing orchards require the ma- jority of the season's supply during the middle and latter part of the season. Where large areas of orchards are found a larger percentage of the season's supply will be needed during August and September than is shown by the tables contained in this report. SUMMATION OF LOSSES TO WHICH WATER OF A PROJECT MAY BE SUBJECT. The investigation has shown : (1) That seepage and evaporation losses in the main canal of a project may range from 10 to 50 per cent, and that the average for most projects is fully 30 per cent of the total amount of water diverted. (2) That the seepage and evaporation losses in the internal lateral system of a project range from 5 to 15 per cent with a prob- able average of 7.5 per cent. (3) That the deep percolation losses on the farm range from 10 to 80 per cent and will probably average 20 per cent. (4) That the surface waste from a farm will range from 5 to 50 per cent of the amount delivered, and should average approxi- mately 12.5 per cent. (5) That the evaporation loss of the amount retained on the farm will range from 6 to 12 acre inches, or from 10 to 50 per cent of the amount delivered. It is hardly probable that the water which is delivered to any particular individual on any particular project will suffer the maximum loss from each and all of the above sources, though it is entirely possible. A careful study of the above summary shows that but an exceedingly small part of the amount that is diverted at the head of the main canal is, or ever can be, absorbed and transpired by the plants. The above losses represent actual determinations for the most part, and Avhile they can never all be elimi- nated, a study of the above tabulation shows strikingly that the present average irrigation practice is indeed a very wasteful one. The losses in the internal lateral system and in the 170 REPORT OF STATE ENGINEER. main canal of a project might be almost wholly eliminated, liOAvever, in cases where the saving would justify the ex- pense, by lining all canals -with concrete or by conveying the water in pipes. Deep percolation losses and surface waste from the farm might also be almost entirely elim- inated by careful preparation of the land and skillful ap- plication of the water. Evaporation loss that takes place from the fields, however, can never be entirely eliminated, but may be materially reduced by the application of water in deep furrows, and thorough surface cultivation. The above discussion should clearly indicate that in by far the majority of cases the value of the irrigation water has a greater influence on the Duty than all other factors to- gether, for it is quite plain that the greater part of .the water that is now diverted is lost before it can be used by the plants and that most of the losses that irrigation water is now subjected to can be eliminated where the sav- ing will justify the necessary expense. That there is, much less water required for the actual use of the plants than most irrigators realize is amply demonstrated by the large yields that are being secured with very small quanti- ties of water in Southern California and other places wliere water is very valuable. Any one who has studied irrigation conditions elsewhere will be compelled to admit that a large amount of preventable waste is now being experi- enced in Idaho and other places where water is cheap. Economic conditions do not warrant saving all of this waste today, but there is no doubt but that the time is fast approaching when better systems must be constructed. PROPER DUTY FOR IDAHO PROJECTS. The results of the investigation indicate that a normal Idaho project with deep medium clay loam soils should furnish sufficient Avater so that 2 acre feet can be retained upon each and every irrigated acre during the season. That this amount should be delivered under a rotation system in heads of such size that economical use can be secured, and that where a project is devoted one-half to grain and the other one-half to alfalfa or crops requiring a similar amount, 18.65 per cent of this two acre feet should be de- livered during May, 28.42 per cent during June, 32.85 per cent during July, 16.78 per cent during August, and 2.32 per cent during the first one-half of September, there being REPORT OF STATE ENGINEER. 171 but little need for water during the month of April, and practically none after the middle of September. It has been shown that there must be delivered to the farmer ap- proximately 2.25 acre feet per acre at the farm if it has a normal slope, in order for him to retain two acre feet upon the land, but that the amount delivered must be increased where steep slopes are irrigated. The excess that is deliv- ered over and above the two acre feet per acre will be large- ly caught up in lower laterals and drain ditches, and a con- siderable part of it can be delivered again to other users. Where projects consist all or in part of porous soils, or of soils with porous subsoil lying closer to the surface than six feet, more than 2.25 acre feet per acre should be deliv- ered to the consumers, the amount required being largely dependent upon the porosity of the soil. In a general way the required Duty for a soil can be de- termined for any crop by determining, (1) how many ir- rigations the crop will require during the season, and (2) the amount of water the soil will require per irrigation. In order to illustrate how the data contained in this re- port can be used for determining the size of a project that can be irrigated from a certain definite water supply, the following purely fictitious project will be used as an ex- ample : Let it be assumed that an earth reservoir can be con- structed to impound the total annual run-off of a stream which averages 150,000 acre feet, and that a large body of good deep clay loam soil with an average topography can be irrigated by a main canal 20 miles in length. T(here are but little dependable data in existence in re- gard to reservoir losses. This investigation has not fur- nished any light on the subject. An annual loss of 20 per cent of the gross amount of the run-off from seepage and evaporation in the reservoir Avould, however, be the very least loss that it would normally be safe to assume. This would render available 80 per cent of 150,000 acre feet, or 120,000 at the reservoir outlet. Seepage losses in the 20 miles of canal and in the laterals should then be deter- mined by allowing for not less than one cubic foot of loss per day from each square foot of wetted area in the canals and laterals throughout the irrigation season. This would in the above case amount to an additional loss of fully 20 per cent in transmitting the water from the reservoir to the 172 REPORT OF STATE ENGINEER. individual farms, and would allow of a delivery of 96,000 acre feet to the farms. Assuming that the soil was of good character and not inclined to be porous, 2.25 acre feet would be required for delivery to each acre. Ninety-six thousand acre feet would furnish 2.25 acre feet for 42,666 acres. If there was an average of two acre feet retained on each acre, 0.25 acre feet per acre would be wasted or a total of 10,666 acre feet. Fully one-half of this waste should be again caught up and measured out to other con- sumers and would furnish two acre feet per acre for an ad- ditional area of 2,666 acres, making a total net area of 45,332 acres that could actually be irrigated from the water supply. The survey of waste land showed a percentage unirrigated of 8.06. Assuming that 10 per cent of this project Avould never be irrigated because of roads, both county and private, railroad rights of way, and other un- irrigated spots of all kinds, it will be seen that water would be required for but 90 per cent of the gross* area of the project. This would increase the 45,332 acres to 50,369 acres as the gross area of the project that could be irri- gated under normal conditions by a stream with a gross annual run-off of 150,000 acre feet, provided there was suf- ficient storage capacity to retain it until needed. The investigation has demonstrated the adequacy of two acre feet per acre for diversified crops on the better class of soil, but it requires careful husbandry to render this amount adequate, and it seems very evident that but few projects will ever exist in Idaho where an allotment of less than this amount would be justified. It is believed, however, that the amount of water that will produce the maximum yield of crop on any certain class of soil, is in but few cases the proper and economic Duty. It is very evident, and the author wishes to strongly emphasize the fact, that the cost of land, of water, the value of the crops produced, and the costs of producing them, as well as the amount of water that will produce the largest yield, must all be taken into consideration when determining the Duty for any project. The largest crop has been produced in many cases where the most water has been applied, but the yield has been in but few cases^ proportional to the amount of water re- quired, and in view of this there is no doubt but that, broadly speaking, one would be justified in opening up a project with a higher Duty of water in places where water REPORT OF STATE ENGINEER. 173 is very valuable and land comparatively cheap, than where land is high and water comparatively inexpensive. The allotment of the proper amount of water for an irrigation project, however, is a very serious problem, and one that must be given the most careful consideration, for it is fully as vital to err on the side of too little water as it is on the side of too much water, and vice versa. GENERAL SUMMARY. 1. The Duty of Water Investigation, of which the pre- ceding pages are a detailed report, has covered four sea- sons, during which time water has been accurately meas- ured on 529 individual tracts consisting of a total area of slightly over 3,600 acres. These tracts have included all of the staple crops and soils common to South Idaho. The water diverted and used by seven different canal systems in 1011, and eight different systems in 1912 w r as measured. Seepage losses have been determined on 118 different sec- tions of different canals with a total lineal length of 287.31 males. A total area of 16,065.21 acres, including all or parts of 26 sections, has been surveyed for the deter- mination of the waste or non-irrigated acreage contained in a project. In addition to the foregoing measurements and determinations a large number of supplementary in- vestigations have been made. 2. The cost of the investigation . for the four seasons from its inception in the spring of 1910 up to and including January 1, 1914, was slightly over $55,000.00. 3. The Duty of water depends upon a variety of factors which are in the apparent order of their importance : (1) character of soil and subsoil, (2) fertility of soil, (3) cli- matic conditions, (4) diversification of farm crops, (5) use of rotation, (6) preparation of the land, (7) kind of crop, (8) fall plowing, and other factors of lesser im- portance. 4. The following factors and conditions tend to de- crease the Duty: (1) porous soil, (2) infertile soil, (3) cheap water, (4) careless use, (5) poorly prepared land, (6) small irrigation heads, (7) poorly constructed leaky ditches, (8) continuous flow method of delivery, (9) lack of cultivation, (10) large acreages of alfalfa and pasture, and other crops with large Avater requirements. 5. The following factors and conditions tend to in- crease the Duty: (1) deep soil of fine texture, (2) an REPORT OF STATE ENGINEER. underlying strata of hard pan, (3) expensive water, (4) careful skillful use, (5) well leveled land, (0) large ir- rigation heads, (7) short runs, (8) use of rotation systems, (9) diversification of crops, (10) well constructed irriga- tion systems with small transmission losses, (11) fall ploAv- ing and intensive surface cultivation, (12) large acreages of winter "Tain, cultivated crops and orchard, and other crops of low water requirements. 6. The amount of water required by a project depends upon: (1) the Duty of water at the land, (2) losses in reservoirs where water is stored, (3) transmission losses from the point of diversion to the land to be irrigated, and (4) the proportion of a project that is ultimately irri gated. 7. The required duty for a crop on any soil can be roughly determined by ascertaining, (1) how many irriga- tions the crop will require during the season, and (2) the amount of water the soil will require per irrigation. 8. The Duty far projects planted to diversified crops on the average clay loam soils of South Idaho should be sufficient so that two acre feet per acre can be retained on each irrigated acre. 9. A sufficient quantity should be delivered to each in- dividual over and above the two acre feet so that he may, if unavoidable, waste not to exceed 12.5 per cent of the water delivered to him. 10. Fertile soils require less water for the production of the same crop than infertile soils. 11. A tight impervious soil that roots can penetrate in- creases the Duty. 12. More water is required Avhere porous subsoils exist. 13. Gravelly soil may require two or more times; as much water as the medium soil, the amount required de- pending upon the porosity of the soil, the distance water is flooded and the preparation of the land for irrigation. 14. As much as 80 per cent of the water applied to gravelly soil is sometimes lost to the use of the crops from deep percolation. 15. Gravelly soils should invariably be irrigated by flooding large heads of water short distances. 16. The light summer rainfall common to South Idaho has but little effect on the amount of irrigation required. 17. Cultivated crops, all other things being equal, re- quire less water than uncultivated crops, as the loss from REPORT OP STATE ENGINEER. 175 evaporation can be reduced by thorough surface cultiva- tion. 18. Fall plowing tends to materially increase produc- tion and decrease water requirements. 19. Grains and cultivated crops in general require less irrigation water than the other common crops of South Idaho. 20. Winter grains require less water than spring grains. 21. The time of application has a decided effect upon the yield of grain. 22. Grains require the largest amount of water at the flowering or soft dough stages. Alfalfa, clover and pasture should be kept uniformly moist throughout the season and require almost exactly twice as much water on the same soil as the grains. 23. Alfalfa has a decided tendency to increase in yield as the amount applied is increased until at least as much as four acre feet per acre have been applied. 24. While some crops increase in yield as the amount of water applied is increased, the increase in yield is rarely proportional to the increase required in the amount of water. 25. The average waste from grain fields has been 25.3 per cent and 19.1 per cent from alfalfa. The Duty for a project should be so fixed that 12.5 per cent of the amount delivered to a farm may be wasted. 26. Diversification of crops greatly increase the Duty. 27. Very little water is required for a project either earlier than May or later than August. 28. The average length of the irrigation season for al- falfa for the four years of the investigation was 97.6 days, and 42.5 days for grain. 29. The need for water is not constant during the sea- son for projects with diversified crops. About one per cent of the season's supply is required during April, 18 per cent during May, 28 per cent during June, 32 per cent during July, 16 per cent during August, and about 2.5 per cent during the first half of September, after which there is very little need for water. This is shown in detail by the table on page 103. 30. Over 60 per cent of the total supply for the season is required by a project devoted to diversified crops during the months of June and July. Owing to the large demands 176 REPORT OF STATE ENGINEER. of the crops during these two months but few canals can deliver more than is required during: this period. 31. The use of rotation systems and large irrigation heads decrease the net amount of water required during the season. 32. Normal canal systems, particularly where water is inexpensive, divert far more water than is actually re- quired both early and late in the season. 33. The amount of water that will produce the largest yield of a certain crop on a certain soil is not always the economic Duty. 34. The value of land, the cost of water, the value of the crops produced and the cost of producing them, as well as the amount of water that will produce the largest yield, must all be taken into consideration when determining the economic Dutv for any project. 35. Sufficient water for the production of profitable and nearly maximum crops must be delivered to the indi- viduals in order that a project may be successful, but a higher Duty is justified in cases where water is very val- uable and land comparatively cheap than where water is cheap and the land is valuable. 36. The expression of seepage losses as per cent of loss per mile is misleading. 37. Seepage losses should be expressed as the unit of loss per unit of wetted area of canal bed per unit of time. 38. Evaporation losses from canals are negligible. 39. The percentage of loss is extremely high in small laterals carrying one second foot or less. 40. Losses from canals in medium soil range from 0.5 of a cubic foot to 1.5 cubic feet per square foot of canal bed per 24 hours. 41. Porous irrigated land above a canal may cause it to gain instead of lose. 42. Canals should be laid out through compact soils where possible, and should be designed with as small a wetted perimeter as possible. 43. Ninety per cent of a normal Idaho project is irri- gated each year. The total waste and unirrigated areas sel- dom equal 10 per cent. 44. Where rotation systems are used the interval be- tween rotations should seldom exceed from 10 to 14 days. 45. There are now at least 163 electrically operated pumping plants in the vicinity of Weiser and Payette. REPORT OF STATE ENGINEER. 177 46. The plants tested during 1913 pumped varying amounts of water, the amounts pumped per acre ranging from 0.4 to 5.99 acre feet. The costs of the power for pumping varied from $.54 per acre foot to $6.50, and per acre irrigated from f 1.77 to $7.00. 47. There is not sufficient incentive to save water where a flat season rate is paid for power. 48. The investigation indicates that the cost of lifting water over 100 feet with small plants is at present prohibi- tive. 49. Serious loss and waste of power is now taking place in many instances due to faulty design and cheap careless installation of the plants. Small and medium sized plants should develop efficiencies of at least 50 per cent and only such plants as can be guaranteed to do this or better should be installed. 50. Successful irrigation in Idaho under present eco- nomic conditions demands that at least two acre feet per acre be supplied for, and retained upon, each irrigated acre. M83628 THE UNIVERSITY OF CALIFORNIA LIBRARY