UNIVERSITY OF CALIFORNIA • COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY 4, CALIFORNIA HYDROLOGIC STUDIES IN COACHELLA VALLEY, CALIFORNIA M. R. HUBERTY, A. F. PILLSBURY and V. P. SOKOLOFF June, 1948 UNIVERSITY OF CALIFORNIA • BERKELEY, CALIFORNIA CONTENTS Page Introduction 1 Summary and conclusions 1 Water quality 1 Ground water levels 1 Reclamation 2 Features of the Valley 2 Geography and physiography 2 Climate . . 3 Water supply 3 Soils 5 Development ..... 5 Water quality 5 Chemical characteristics of surface waters 5 Chemical characteristics of ground waters 6 High nitrate waters 8 Low magnesium waters and soils 10 Ground water levels . 10 Salt removal from Valley soils 17 Leaching 17 Experiments on leaching 17 Laboratory studies of leaching 23 Flushing 23 Reclamation and drainage 24 Literature cited 31 HYDROLOGIC STUDIES IN COACHELLA VALLEY, CALIFORNIA M. R. Huberty,' A. F. Pillsbury, and V. P. SokolofT INTRODUCTION Present irrigated agriculture in Coachella Valley, a part of the Colorado Desert, is based upon utilization of the ground water. For a number of years the U.S. Bureau of Reclamation, in contractual agreement with the Coachella Val- ley County Water District, has been in the pro- cess of bringing in a supplemental water supply from the Colorado River through the All -American Canal System. This new supply will cause an ex- pansion of agriculture in the Valley. It will also change the character of such reclamation problems as drainage, Irrigation practices, suitability of various soils for Irrigation, and the chemical nature of some ground waters. To develop fully the Valley's resources re- quires both a knowledge of its hydrology before importation of Colorado water and a continuing study of the changes wrought by that importa- tion. In 1936 it was found that, while a num- ber of studies of the Valley had been made (l, 3, 10, 11, 12)*, none contained a detailed hy- drologic picture, particularly with relation to the quality of the water and the reclamation of saline soils. The study reported herein was therefore begun the following year. In this study the quality of surface waters recharging the ground water basin was investi- gated, and the meager information on the quan- titative flow of such surface waters was sum- marized and evaluated. An intensive survey was made of the quality of the ground water through- out the Valley, and peculiarities found were studied as to their cause and effect. Informa- tion on ground water levels was extended, in- terpreted, and summarized. Finally, the feasi- bility of reclaiming the saline soils which are found in parts of the Valley was investigated. The cooperation of the Coachella Valley County Water District, the U.S. Department of Agriculture, Division of Irrigation Agriculture, and many farmers and well drillers was very helpful. Their assistance is gratefully ac- knowledged. Interpretation of the practical agricultural implications of these data are not fully pre- sented here. Such interpretations, along with recommendations on irrigation practices, can be obtained through the Agricultural Extension Service . SUMMARY AND CONCLUSIONS Water Quality Perennial surface streams draining into the Valley, and the predominant ground waters, have a characteristic low salt content. The percentage of sodium, as of total cations, * Numerals refer to bibliography on page 1 , 1 Professor of Irrigation and Irrigation Engineer in the Ex- periment Station. 2 Associate Professor of Irrigation and Associate Irrigation Engineer In the Experiment Station. ^Former Junior Soil Chemist in the Experiment Station. In the ground water increases down the Valley, but the amounts of the total dissolved constit- uents do not similarly increase. In the lower valley trough, sodium percentages reach an ob- served maximum of 96, increasing from a minimum of 21 in the upper valley. Where irrigation water with a high sodium percentage is used, the soil structure is im- paired, and rates of water entry into the soil are decreased, often creating irrigation and reclamation difficulties. In the long run the effect of high sodium percentage will be great- est on fine- textured soils and least on coarse sands, but it will be noted more quickly on the coarse- textured soil. Magnesium content of the ground waters de- creases down the Valley. These data indicate the possibility of a magnesium deficiency for certain crops, but investigation of that point did not come within the scope of this study. Not all ground waters of the Valley have a low salt content. A number of wells contain waters of a moderate to high salt content, but such waters normally do not have a high sodium percentage. In general, the waters of moderate to high salt content were found in the follow- ing areas : 1. The Garnet-Seven Palms Valley region. 2 . Along the northeast edge of the Valley near a region where faults are known to ex- ist. 3. Some relatively shallow wells in the central trough of the Valley which are prob- ably affected by return waters from irri- gated lands . 4 . Shallow waters in the Indian Wells district. 5- An area at the lower end of the Mecca Canyon alluvial fan. 6. Oasis and South Salton regions below the Martinez Canyon alluvial fan. In the Indian Wells district, particularly the more shallow wells yield water- of surpris- ingly high nitrate content. Evidence indicates that the area was at one time covered with ex- tensive mesquite forests. Under natural condi- tions there was not enough moisture to permit decomposition of the leaves and twigs, so large amounts of litter, high in nitrogen content, ac- cumulated under the trees. When the lands were levelled and irrigated, the organic matter de- composed and the nitrates appear to have leached downward into the ground water. The nitrate con- tent of the water fluctuates, and generally ap- pears to be decreasing in amount. Ground Water Levels In the past, estimates have been made of the "safe yield" of Coachella ground water- -the rate at which it can be pumped throughout the Valley without exceeding the supply. It is our opin- ion that there are not sufficient data avail- able to make an accurate estimate of safe yield. Certainly the supply appeared to be adequate for the irrigated area of the period 1936-39, and could possibly be adequate, with careful use, for a greater area. During that period with- drawal from wells appears to have been about IOC, 000 acre.-feet a year. Some farmers will and have experienced localized difficulties in obtaining enough water because of interference of wells, or because of flow restrictions due to faulting along the sides of the Valley. Increasing development of the Valley, with increasing demands for water, causes a progres- sive drop in water levels. The ground water can be visualized as a percolating body of water moving from the mountains to the lower trough, where, under natural conditions, it was lost by evaporation from the soil, transpiration from native plants, and seepage to Salton Sea. When water is withdrawn from wells for irrigation, the water level downstream is lowered, thus re- ducing these natural losses. The data indicate that water levels upstream from the irrigated areas have been little affected by downstream pumping. Despite great seasonal fluctuations in re- charge from surface streams, the main seasonal changes in ground water levels are those caused by pumping. This relative stability is indicat- ed by the fact that no .appreciable changes in water level appear in wells upstream from irri- gated areas, and is due to the combined effect of a low rate of ground water movement and large underground storage. Apparently only a long cycle of wet or dry years would significantly affect the supply. Lowering water levels cause an increase in cost because of the greater distance the water must be lifted. Also, increased capital out- lays may become necessary to lower pump bowls, etc. However, there appears to be considerable opportunity to cut down waste and to increase pumping load factor, i.e., smaller pumps could be kept running more hours per year through use of regulating reservoirs, irrigation practices could be revised, pumping plants could be oper- ated by a group or by a Water District. If, upon the utilization of Colorado River water, all pumping of native water were to cease, a marked rise in water levels would occur. The area in the lower trough required for natural discharge (by seepage, evaporation, and transpiration) of the ground water flow would increase. Such an area would have a water table very close to the surface. However, plans for development will certainly include consideration of this problem, and there is no reason to believe a marked rise will occur, if pumping of Valley water Is continued and the drainage program is adequate. Reclamation Most of the soluble salts in the more per- meable saline soils are near the soil surface, and can be removed by leaching and flushing with water. Flooding with local water of low salt con- tent, but high sodium percentage, causes a marked movement of salt through the soil pro- file of most Valley soils. In some instances this may be hindered by stratification, but re- lief may be obtained by deep plowing or sub- soiling where such strata are close enough to the surface to be so .broken. Also, lateral drainage may occur above such strata. By flushing water over the surface of saline soils for a short interval prior to leaching, large quantities of surface salts may be re- moved without passing through the soil profile. Although the effective period is of short dura- tion, this method can be repeated with good re- sults whenever salts accumulate at the surface of the soil. When borderline saline soils are under regular irrigation, It is good practice to flush the first water over the soil, and waste It from the lower ends of the Irrigation system. The data Indicate that when local water is used on some soils in the lower trough of the Valley, infiltration rates are too low to main- tain a low salt balance In the soil under nor- mal irrigation and cropping programs. This ef- ^ feet is exaggerated in the studies reported W here, because the soil was kept continuously wet. Under normal Irrigation, the soil's dry- ness before each application would result in increased infiltration rates. Nevertheless, It would be difficult to maintain a thrifty crop- ping program with local water on many of the soils now saline. Colorado River water, with a favorable sod- ium percentage and moderately high salt content, should have a better rate of entry Into the soil. Less sodium means better soil structure, and the higher salt content makes it improbable, with free drainage, that composition of the soil water could be altered enough to become detri- mental in any way to soil structure. Labora- tory studies have shown an improvement in per- meability where Colorado River water was com- pared with local high sodium percentage water, although these experiments do not bring out the maximum benefits that might be evident after soils go through wetting and drying cycles. It is believed that most of the Coachella Valley saline soils can be reclaimed with Colorado River water, provided the water table Is kept at a reasonable depth. This statement does not apply to Indio clay or Woodrow series soils, which should be considered unsatisfac- tory until, and if, experimental evidence is accumulated to the contrary. As previously stated, extensive importation of water will produce excessively high water tables unless protective measures are taken. Drainage is therefore a necessary part of any irrigation development program for the Valley, but should not be a barrier to successful agri- culture . Ground water flow appears to be predominantly a lateral movement in discontinuous strata some- what parallel to the surface topography. This factor suggests that the Interception principle of artificial drainage can be employed. It can be expected that there will be local- ized temporary perched water tables here and there throughout the irrigated areas, as there are at present. These have caused crop Injury, although not contributing greatly to salinity. GENERAL FEATURES OF THE VALLEY Geography and Physiography Coachella Valley, a triangular- shaped grab- en, lies at the northwestern end of the Colorado Desert, in the south central part of Riverside County, California. It is bounded on the west and north by high mountain ranges, on the east- ern side by badly broken Tertiary sedimentary deposits (locally known as the Mud Hills), and on the south and southeast by Salton Sink. The w valley proper varies In elevation from 245 feet below to about 500 feet above sea level. While the origin of this valley is generally ascribed to block faulting, there is a lack of agreement regarding the sequence of geologic events Blake (2) , Mendenhall (10), and Brown (3) con- tend that in a period that is geologically very recent Salton Basin was an extension of the Gulf of California, and that it was isolated from the latter by building of the Colorado River delta. The Colorado River then discharged to the north forming Lake Cahuilla, a fresh water lake with a surface elevation some 40 feet above sea level. In time the Colorado River shifted its course to the south, leaving the lake to disappear through evaporation. Free (6) and Buwalda (4) contend that the present Salton Sink was never an arm of the sea but rather that it has settled as a block be- tween two fault lines in such a way as to ex- clude the entrance of the sea. The present Salton Sea has been in existence since 1905, when the Colorado River breached its levees and flowed into Salton Sink until February, 1907- Since then a sea has been main- tained by drainage and spill water from Imperial Irrigation District in Imperial Valley. Old settlers reported that large quantities of flood waters from the Colorado River entered Salton Sink In 1840, 1849, 1852, 1859, 1862, and I867. The amount entering in 1862 was said to have been extremely large (5)- This water must have evaporated within a few years for King (8), in describing a trip through the Val- ley in May, 1866, makes no reference to a large body of water. Climate United States Weather Bureau records for Indio, which extend over a period of about 60 years, indicate a mean annual rainfall of 3 inches, a portion often coming from summer thunder storms, and a mean average temperature of 73 F. The highest recorded temperature for this station isl25°F., the lowest l6°F. Water supply Whitewater River, which rises on Mt. San Gorgonio, traverses the main axis of the Valley and empties Into Salton Sea. Table 1 lists the watersheds. Of these, the San Bernardino and the San Jacinto mountain groups form the impor- tant streams. Although the watershed has an area of about 1200 square miles, the mean annual discharge Is not large, since the greater part of the shed is desert. Only during flood stage does surface water reach Salton Sea, as the nor- mal flow quickly enters the highly permeable alluvial fans. In fact, with the exception of a small area In and above Palm Springs, all ir- rigation water in Coachella Valley Is now ob- tained from wells . Measurements of the amounts of water enter- ing Coachella Valley are very deficient. The U. S. Geological Survey made a few Isolated readings at the end of the last century, and for a number of years the Coachella Valley County Water District made measurements on eleven streams discharging into the Valley. Unfortunately these measurements were made in- termittently. As it is not feasible to reach most of the stations during flood period, when the run- off during a few days might exceed the combined run-off for the remainder of the year, the figures given do not truly represent total flow. They do indicate that the flow varies widely from year to year, and that the highest sustained run-off occurs during April. White- water River, Snow, and Tahquitz Creeks are per- ennial streams from their source to the edge of the Valley. Name TABLE I . WATERSHEDS OF COACHELLA VALLEY Approx. area * in sq. miles Little San Bernardino M't'n group San Bernardino M't'n group Morongo Canyon group Mission Creek Whitewater River Cottonwood-Stubby-Lyon group Millard Canyon Hathaway-Potrero group San Gorgonio River San Jacinto M't'n group Banning-Cabazon group Snow-Fails group Chlno Canyon group Tahquitz Canyon Andreas group Murray Canyon West Palm Canyon 430 296 100 46 62 22 16 22 28 135 40 23 18 20 14 10 10 Santa Rosa M't'n group 335 Palm Canyon 92 Cathedral-Magnesia group 18 Deep Canyon group 65 Guadalupe-Toro group 48 Martinez-Agua Alta group 52 Barton Canyon group 60 * Data are principally from Tait (12) 3 Approx. range in elevation. Ft. above sea level not known 1400-11485 1400-8966 2500-9500 1400-11485 1800-6607 2500-7700 2500-7900 2600-9300 800-10805 1500-7800 1250-10805 900-10805 500-10600 800-8400 800-8900 800-7600 100-8705 800-8046 400-3000 500-8705 100-6539 600-8705 500-6650 \ n£v ,-i- %»■■£' Date palms arch over irrigation waters in Coachella Valley, (credit: U. S. Bureau of Reclamation) FLOW OF 11 STREAMS ENTERING COACHELLA VALLEY* In Cubic Feet Per Second 1936 1937 1938 January — February 64 March 55 — April 118 305 May 82 — June 66 194 242 July 51 August 53 101 103 September 44 October 46 .68 94 November — — December 67 *0n basis of one measurement per stream, usual- ly made near the beginning of the month of the record. Measurements not made during flood. Soils During 1923, Kocher and Harper (9) made a soil survey of the major portions of the po- tential agricultural land in Coachella Valley, an area embracing 220, 160 acres. Of the area surveyed, about one fourth is composed of Coachella soils, one fourth Indio, and approx- imately one fourth Superstition soils, the re- mainder being made up of rough, broken land, Woodrow soil, and dune sand. The Coachella and Superstition soils are light gray in color, relatively coarse textured, calcareous through- out the soil profile, and often wind-blown. The former has been derived from igneous rocks high in quartz, the latter from rocks of mixed origin. Agriculturally the Coachella series is better than the Superstition, since most of the latter is extremely coarse. The Indio series is represented by recent alluvial brownish-gray soils derived from ig- neous rocks high in quartz. In general, these soils are finer textured than the Coachella series, because they have been deposited far- ther down the slope where the grade is flatter. The finer textured soils of this series are located in the trough of the Valley, and often contain large amounts of salines. The Woodrow series, lake-laid soils, are con- fined to the area between the present beach line of Salton Sea and that of 1907, when the present sea was at its maximum height. These are heavy- textured saline soils of mixed origin. The soil survey report (9) contains an "al 7 kali" map. It shows that much of the land in the original zone of flowing wells is strongly saline . Generally speaking, all the soils are highly micaceous, with a resultant predominance of flat elongated soil particles. The soils do not tend to pack unduly, even under use of heavy grading and cultivating equipment. Often they have extremely low volume weights, and in fills tend to bulk excessively until wet down. A remarkable amount of small fresh-water shells are found throughout most of the soils, but these shells decompose very slowly. Coachella Valley by the Southern Pacific Com- pany in 1879- Under the terms of the agreement between the railroad and the Federal Government every other section of land throughout the Val- ley became the property of the railroad. A greater part of the non- railroad land was filed upon during I885 and 1886 under the provisions of the Desert Act. However, it was not devel- oped at that time. In 1894 the railroad company drilled a deep well at Mecca (then known as Walters), proving the presence of an abundant supply of good qual- ity artesian water. It was not until 1900, how- ever, that well drilling in this Valley was suc- cessful. At that time a hydraulic well -drilling rig was employed to drill a well at Indio. The result was so favorable, 500 feet of well being drilled in 7 hours, that by 1907, (10) there were about 4oo wells in the region between Indio and Salton Sea, about three quarters of which were flowing. Mendenhall (10) reports that in 1905 the zone of flowing wells extended as far up the Valley as Indio. Agriculture has gradually moved up the Val- ley away from the fine textured, saline soils. At present many of the original farms have been abandoned . A crop survey made jointly by the Coachella Valley County Water District and the University of California in 1936-37 showed the following acreages: alfalfa, 1496, cotton 1460, citrus 2461, dates 2644, citrus and dates 552, figs 48, truck crops 3655, table grapes 2280, pecans 46, pasture 901, total 15,543(11). WATER QUALITY In these studies samples of both surface and ground water were examined, but the em- phasis was placed on ground water because pres- ent Irrigation in the Valley is almost exclus- ively by wells, and because chemical composi- tion of ground water might indicate the nature of ground water movement. Chemical Characteristics of Surface Waters The chemical composition of water samples collected mainly in April, 1937, and June, 1938, from the principal surface streams drain- ing into Coachella Valley Is shown in Table 2. The approximate flow observed when the samples were collected is also given. These figures are not a good indication of the yield of the watersheds because of wide fluctuation in flow and extreme variation, from stream to stream, in infiltration above point of sampling. Using the limited run-off data as a means of weighting electrical conductivity values for each stream, the mean conductivity for all sur- face streams appears to be approximately 320 micromhos/c'm at 250c.* Development of Coachella Valley A railroad line was completed through Electrical conductivity of Irrigation waters was previously commonly reported as K x 10/ at 25° C. Data reported on the old basis can be converted to the new standard by mul- tiplying by 10. Chemical Characteristics of Ground Waters Chemical analyses of 118 wells and 2 springs in the Coachella Valley area, together with such pertinent hydrological data on the parti cular wells as it was possible to obtain, are presented in Table 3. On an average, about one-fifth of all wells in the Valley were test- ed. In districts where unusual chemical char- acteristics prevailed, such as in the Indian Veils and Oasis areas, a considerably higher per cent of all wells was tested, while in areas of more uniformity the percentage was smaller. On the whole, the data are represen- tative of all known ground water conditions in the* Valley. The information on well depth and perfora- tions was obtained mainly from well drillers, farm operators, and any other sources available. For various reasons such data are not always accurate, but sufficient cross-checking was done to establish a reasonable degree of re- liability. The depths to water were measured when feasible; otherwise the most reliable past record or estimate was used. Data on acreage, by actual survey, and certain of the other data were obtained at the same time in connection with other investigations (ll). Figure 1, (page 24) a map of the main por- tions of the Valley, shows the locations of the wells sampled. A code number, adjacent to each well, indicates the type of water as re- gards electrical conductivity and sodium per- centage. The map also shows ground water con- tours and Irrigated areas. The former will be discussed later. The approximate limits of ir- rigable land were obtained by excluding all land on the periphery of the Valley coarser than Superstition sand (9). Non-irrigable areas, such as dune sand, within the Valley proper, were not excluded because of inade- quate data. The limits shown are Intended only as an indication of the gross irrigable area, and should not be interpreted too closely. While comparisons on a valley-wide basis show wide ranges in water characteristics, composition within local ground water basins is usually rather uniform. Certain data, given in detail in Table 3, are summarized in Table 4. Variations in electrical conductivity in- dicate differences in saline content. The high conductivity water is normally found in shallow wells, or in wells drilled Into the older alluv- ium at the edge of the Valley. From a relative- ly low sodium per cent water in the wells of the upper part of the Valley there is a grad- ual increase toward the lower end where sodium percentages of 90 are common. Variations In magnesium content are listed. Depths of well perforations and water temperatures are also given. The character of the ground water is Influ- enced largely by the nature of the watersheds. The main run- off , which has a low salt concen- tration, is from the high, precipitous, and granitic San Bernardino and San Jacinto Moun- tains. Ground waters fed from streams draining these high mountains traverse practically the entire length of the main axis of the long nar- row valley. Palm Canyon, Deep Canyon, Martinez Canyon, and adjacent smaller canyons drain the lower Santa Rosa Mountains, and enter the Val- ley along the south side. The latter drainage basins are much drier than those of the high mountains, run-off is small in proportion, and flashy in nature. To the east and north are the desert sand hills and the dry Little San Bernardino Mountains, contributing only occas- ional flash floods . The Valley fill to an undetermined depth is an alluvium from the surrounding mountains. The ground water moves* in intermingling aqui- fers under pressure through this alluvium. There is undoubtedly considerable mixing, ex- cept when such mixing is hindered by faults or other barriers. In general, structural faults exist parallel to the main axis of the Valley ( on both the north and south sides, being espec- ially noticeable on the north side (3). There is some evidence that other faulting exists. Fault zones, because of the nature and condi- tion of the material, can affect the chemical nature of waters passing through them. Not all the water passing through an aquifer- flows parallel to the static water level; much of it may follow a parabolic pattern and reach considerable depths before appearing again near the surface (7). The environment and time involved for such passage are too un- certain to warrant a rigid interpretation of the hydrology and geology of the area from the chemical analyses of the water. Returning to the specific character of Coachella Valley ground water, inspection of Table 4 discloses that the predominant ground water has a characteristic low salt content. Eighty- three of the 120 samples tested had a conductivity of 500 or less, and averaged 325. Of the above mentioned 83 wells, 36 had a sod- ium percentage of 50 or less, and averaged 35- They are, in general, located all along the Valley above the town of Coachella. Thirteen of the 83 wells had a sodium percentage between 51 and 70. Most of these are in the Coachella- Thermal area. From Coachella to the Salton Sea the sodium percentages were higher as a rule. Figure 2, (page 25) shows the progressive In- crease in sodium percentage for all low conduc- tivity wells (500 or less) down the Valley from Palm Springs to the Salton Sea. As the conduc- tivity of the water down the Valley is fairly constant, the increase in sodium percentage re- presents an increase in sodium ions accompanied by a decrease in calcium and magnesium Ions. Our information concerning the wells with conductivity above 500 is as follows: a. Two of the three wells tested in the Garnet-Seven Palms Valley district, a somewhat Isolated area, are of higher conductivity than waters in the Valley proper. The third has a moderately high sodium percentage . b. Two wells and one spring near the mud hills north of Indio, an area where major faults run parallel to the main axis of the Valley, have water of relatively high salt con- tent. This region has never been very produc- tive of ground water. c. In the central trough of the Valley south of Indio and Coachella are 5 relatively shallow wells which have more saline water than most of the wells of similar depth in the re- gion. Three of these have top perforations from 85 to 128 feet below the surface, and two have gravel envelopes with top perforations 120 and 200 feet, respectively, below the surface. There are indications that deep seepage from the extensive overlying irrigated lands is re- sponsible for the increase in salines. | d. Twelve wells with water of higher than average conductivity are in the Indian Wells district near the edge of Deep Canyon cone. Here, ground water contours indicate a slight influence on water levels of Deep Canyon water, and a subterranean barrier formed by the pro- CH rH . OO . 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S S " ■• n n - qj O ■H 3 Si EsH* ;* ^-4»fa fa fa fa O K s www o ^ o o o o O O CD ® bo o • ■ CO o o o o • O r-( > c -Vr-!^ fa fa fa ^ *■ ■ - fa fa fa fa fa fa fa fa Ql O •H SJtJP^ +J +J fa fa t. P P ft-,H W w w p -p p p p p ^ £) fa rH H *J o o o o o o o o O O OSS CO CO o co to rH ft 1 fa fa • «Hj o o o - •H +j +j fa fa ;i fa fa ^ W td fa fa ^ f, fa fa fa fa fa fa fa fa fa fa O *H CO o o s K co S K CO S S ssojaa ass -s s • ss S S HS rH s CD fa — OQ fa O O a P. -ri *-i fa fa •CO G C p a> n* w-^ o o fa fa fa fa fa -p -p t» WfcO 43 J3 X) P, N o; C G a) cO -o o o a) fa s-. -p p CO o > 1 o o :* ;* fa fa fa > o o ■H -H 0) cO P->^ ^ £ -^ G G ■H -H OJ 0j cfl o d) moo O -3 3 CD 0) CO 1 1 tH O 0) 01 CO -P P rH OBrlHH fa fa-c p p p c; f > > C rjo- o o -h .G x; fa fa fa a a T3 TJ fa H rH i^5^5 ftp."** 0J OJ fa o sisa O O CO cd cO ;-: ^ x: x a C C 3 fl) cO cO b) cO a) to OJ 0) CO o CO cv, Ql, ffi cO co CO CO O fcH 6-1 < <; Z. Q- P-. &, a, p-. a, a, P Q E tH jection of Point Happy into the Valley. Except for 2 veils in Section 20 (T.5S., R. 6E, in Figure 1) all of the higher conductivity Indian Wells district wells are relatively shal- low, top perforations being from 75 to 129 feet below the surface. No other adjacent wells are perforated closer than 167 feet from the surface, The sandy soil is highly permeable, and heavy irrigations totalling 10 to 16 feet depth per year have been common (11). It Is quite pos- sible, then, that deep percolation from over- lying irrigated lands may influence the salt content of the shallow wells. The two wells in Section 20 are reported to be perforated at depths of. about 420 to 520 feet below the sur- face . The apparent depths of perforation would appear to throw some doubt on the theory that deep percolation from overlying irrigated lands is a causal factor in the higher salt content of these two wells, but do not preclude the pos- sibility, especially since there might be leaks into the wells from shallow strata. The higher conductivity wells in the Indian Wells district have remarkably high concentra- tions of nitrate. This will be discussed later. e. Three wells with water of higher conduc- tivity than average are east of Mecca on the lower end of the Mecca Canyon alluvial fan. Local well drillers report a stratum in this area "high in soda", which stratum is normally sealed off by them. The log for well 7-9 22b Indicated the stratum at 350 to 360 feet depth. The owner states the water was of "excellent quality" until the casing was eaten away at that depth. Water of well 7-9-36 is similar, both being high in Ca, Na, and especially S0^. Surface water levels show the influence of ground water moving down the Mecca Canyon alluv- ial fan. f. Four wells of higher than average conduct tivity are in the western and southern parts of the Oasis area, and seven are In the south Sal- ton area. Surface water levels In these areas are in- fluenced by the flow from Martinez Canyon. The higher salt content, and change in proportions of some ions, are indicative that the waters from these wells may be partially from a sepa- rate source (notably Martinez Canyon) rather from the main valley. For the dominant waters of the Valley, the trend in sodium percentage has been stressed. Of equal importance is the negative correlation of magnesium content with distance down the Valley for wells with conductivity under 1000. This Is illustrated In Figure 2, (page 25), along with the per cent sodium trend. The de- ficiency in magnesium in the lower end of the Valley will be discussed later. The temperatures of the waters in the Oasis and south Salton areas are significantly higher than for waters of comparable composition in t the Thermal-Mecca areas . This abrupt change in water temperature indicates the possible pre- sence of a subterranean barrier. High nitrate waters The high nitrate content of some well waters in the Indian Wells area is an interesting sub- ject on which some time was spent in an attempt to determine the nitrogen source. The first approach was to determine the character of water replenishing the ground water supply. The nit- rogen content of the Deep Canyon surface supply, as well as of the supplies originating in the main streams, was low. Stream waters could, therefore, be eliminated as the source of the nitrogen supply. Growei-s of dates normally use relatively large amounts of nitrogenous fertilizer. As the soils of this section are relatively coarse textured and the amounts of irrigation water applied are large, there is undoubtedly some nitrate leached to the ground water. It is very doubtful, however, that the quantity of nitrogen that has been added by this means would account for the large amounts found In the pumped water supply. In parts of this area, forests of large mes- quite trees are found. Under natural conditions there is a gradual accumulation of litter upon the soil surface, often a half foot in thick- ness. Samples of this litter were found to con- tain 2.3$ nitrogen. Incubation at room tempera- ture of soil samples containing 5$ by weight of litter showed a rapid breakdown of organic mat- ter. Soil samples were taken to a depth of nine feet in a mesquite covered area and from a nearby sagebrush tract. One to five aqueous extracts of these soil samples showed the fol- lowing amounts of nitrate present, expressed as milll-equivalents of nitrate gram of soil. NO o) per kilo- Depth, Mesquite Sagebrush feet 0--1 5.1 7.9 1--2 24.9 * 10.7 2—3 9.3 9-7 3-4 16.4 5.5 4-5 15.7 4.0 5-6 7.4 4.0 6-7 7.1 3.2 7-8 9.6 0.9 8-9 4.5 *This represents about 630 pounds of nitrogen per acre foot of soil, an extremely high value. Analysis of a 1:1 aqueous extract of a soil sample taken from beneath the mantle of litter in a mesquite forest showed the following com- position, expressed as milli-equivalents per liter: calcium, 18.0; magnesium, 5.7; potas- sium, 6.1; sodium, trace; bicarbonate, 1.6; sulphate, 6.3; chloride, 5-1; and nitrate, 17-4. Normally, water extracts of California soils are low in potassium and nitrogen. In this soil sample, however, these . constituents are present in especially large amounts. When mesquite forests are subjugated and the land placed under irrigation an entirely differ- ent environment is established than prevailed under natural conditions. Organic matter is quickly decomposed and soluble constituents are leached to the ground water by heavy applica- tions of -irrigation water. Pumping produces a drawdown in the water table causing a gradient toward the well. Under this condition, shallow wells in particular could become contaminated by soluble material from the overlying irrigat- ed lands. This hypothesis might explain the source of a large part of the high nitrate con- ( tent of some of the well waters. Considerable fluctuation and a gradual reduction in the ni- trogen content can be seen from the analyses. Indications are that decomposing organic matter is the localized source of the nitrogen. CHEMICAL ANALYSES AND HYDROLOGICAL DATA FOR REPRESENTS LLS IH COACHELLA VAL LEY , CALI FGRNIA «. — — -■ depth data wate Cll/l!£C 8 s- lected ;onductivity Na C0 3 HCO-^ SO 4 Total Perforations Static * 1 4 5 6 7 8 9 10 11 12 13 14 I 5 16 17 ie 19 20 22 22 2 h, p.p.m. m.e./l n.e./l m.e./l m.o./l m.e./l 3-"-15 3- 5 -17a 3-5-lp 4-4-14 4- !(-"?: SEi Of SEi KWf of SEi SWi of NWi SW oor., NWi of SEi 710± 800± 800S 450± 430* 203 400 801 550 195-203 342-400 317-350 Hot Spring 180 23 4o 156 180 50 70 152 1.5 1.3 0.1 0.1 13 7-13-38 7-13-38 7-13-38 9- 6-38 7-13-38 85 85 106 67 8.4 8.5 8.1 9.2 7.9 358 1290 liio 356 308 0.03 0.45 0.40 0.23 Tr. 69 60 67 94 24 0.93 3.20 3.20 0.18 1.91 0.19 1.11 1.02 0.45 2.46 8.20 8.41 3.04 O.76 Tr. Tr. Tr. 1.68 0.00 2.34 1.73 1.90 0.15 2.13 0.63 8.56 8.70 0.42 0.32 0.46 2.00 2.09 1.00 0.51 0.03 0.08 0.10 0.00 0.12 4-5-13 1-5-33 4-6-12 1-6-27 Hr. NW cor. Ctr. S. side, HEi NW ccr. HEi Ctr. H. aide, SWi of SWi 430* 250 295 500± 164 500 300 363 791 320-500 202-212, 277-297 295-354 Spring 506-563 128 73 80 '60 166 125 0.3 o.i 0.1 4.0 40 ' 600P 1-28-39 9-12-38 7-13-38 12- 1-37 12-12-36 68 Cold 72 8.0 8.2 7^4 434 344 421 2050 0.05 0.15 0.07 1.39 25 21 21 80 45 2.83 2.06 2.42 3-07 1.20 0.83 0.73 0.60 1.01 1.56 1.20 0.75 0.78 16.52 2.22 0A2 0.00 0.30 3.01 2.36 2.38 2.12 2.85 1.28 0.45 0.72 13.56 0.33 0.32 0.29 0.63 1.78 0.14 0.00 0.04 Tr. 4-6-28 5-5-13 5-6-7 5- 6- 20a 5-6- 20b SE cor. NEi HE cop. NW cor. , , HE cor. SEi of NEi HE cor. SEi of HWi 167 218 223 199 I98 1056 216 267 522 497 192-1056 90-155, 226-236 435-522 420-497 52 90 80 76 100 85 97 98 8.0 0.5 3.0 3.0 2.4 600P 75 „ 170F 170P 7-13-38 12-12-38 8-23-38 1-10-39 1-14-39 72 69 72 71 7.6 8.0 8.0 7.8 7.6 332 436 289 1270 1150 0.02 0.12 0.07 0.05 0.03 29 27 31 3 § 18 1,90 2.52 1.66 7.95 7.60 0.44 O.65 ■O.36 2.02 1.60 0.96 1.30 0.89 4.44 2.08 0.00 Tr. Tr. 2.44 2.47 2.15 3.00 3.37 0.41 1.14 0.35 5.06 3.23 0.31 0.62 0.38 3-70 4.36 0.04 0.19 0.00 2.74 0.14 5-6- 21a 5-6-21b 5-6- 2lc 5-6-22a 5 -6- 22a 5-6-22a 5-6-22b 5-6-22b 5-6-22C 5-6-22C 5-6-22C 5-6-22d 5-6-22e 5-6- 22f 5-6- 22g SW cor. Ej or HEi HE cor. Wj of SWi of HE* SW cor. Ej of SWi of HEi Nr. SW cor. E$ of HEi of SWi 201 192 205 180 156 161 196 192 183 191 320 300 251 203 iio 566 342 250 302 209 Appro*. 220-320 120-1 -,q,iq4-21 3, 235-283 167-192,197-237 100-128,162-170 '98 80 61 '63 '88 loo 112 96 '83 "74 ioi 103 10c 110 1.3 1.4 0.9 1.2 o.i 1^7 ili 0.7 1.3 1.1 70P 59P 59P 10 39> 39P 46' 5 75P 25 12-12-38 12-12-38 12-12-38 10-5 -38 12-19-38 12-15-40 7-13-38 11-17-38 7-13-38 11-17-38 1-14-39 7-13-38 11-11-38 11-17-38 11-17-38 71 70 71 77 75 70 77 73 7.9 7.9 8.0 8.2 8.2 e'.i 8.2 8.2 8.2 8.2 8.2 8.2 8.0 8.1 399 648 399 1480 643 1090 1040 351 341 347 445 770 530 507 0.20 0.02 0.25 0.25 0.11 0.35 6!o5 6!o7 0.10 23 25 30 30 42 44 15 33 34 34 39 29 34 2.17 3.83 2.31 8.30 3-33 3.00 4.86 4.73 1.81 1.82 2)26 3.59 2.74 2.30 0.57 0.88 0.66 0.75 0.73 1.08 1.07 0.47 0.44 6i47 1.01 1.06 1.05 1.33 1.60 1.30 3.96 2.65 4.76 4.66 1.20 1.14 l"57 2.93 1-59 1.73 0.00 0.00 0.00 Tr. 'Tr. 2-34 2.40 2.38 2.46 2.63 2.50 3. It 3.12 2.25 2.21 2.30 2.19 2.19 2.61 2.61 1.05 1.86 1.20 4.47 2.06 4.51 3.97 0.12 0.17 i-23 3.88 2.19 1.05 0.64 1.07 0.59 2.73 2.17 1.06 2.06 1.85 0.60 1.00 0.54 0.74 1.15 0.75 1.00 0.08 1.00 0.09 3-37 3.14 0.57 1.20 1.24 0.60 0.08 0.10 0.03 0.50 0.02 0.30 Hr. SE cor. SWi of NEi Ctr. W aide, SWi of NEi 288-298, 346-404,420-474 SE cor. wi of HWi of SWi SW cor. Hj of SEi Of SWi Ctr W aide, Sj of SEi SW cor. NWi 222-260, 287-340 95-170, 215-220, 260-298 75-100, 106-130, 136-142 5-6-22h 5-6-221 5-6- 22 j 5-6-26 5-6-27 HW cor. SWi of SWi of NWi SW cor. SEi of NWi HW cor. Si of SWi of SWi 300'* 3 of NW cor. Ctr. HEi 186 179 207 158 20C 247 208 545 424 84-126 75-101, 110-125, 222-240 100-545 270-424 'si 108 '95 102 104 121 122 0.9 1.0 0.7 2.5 3.1 20 12 27 100P 256P 11-17-38 XI- 17- 38 12-12-38 11-9-38 5-8-40 72 74 79 8.1 8.2 8.0 770 888 491 2170 558 o!io 0.23 0.11 28 29 39 36 34 4.44 1.93 2.54 U.56 2.73 1.08 1.3* 0.51 2.9ft. 1.10 2.12 2.53 1-95 8.22 . 1.98 0.00 0.30 3.37 2.70 2.63 2.07 2.39 2.03 2.41 1.66 1?.15 2.17 1.55 l.QO 0.70 7.96 0.67 0.89 1.93 0.86 0.04 5-7-3 5-7-6 5-7-12 5- 7- 21a 5-7- 21b 5-7-22 5-7-22 5-7-21 5-7-25 5-7-26 HW cor. SWi Hr. HE cor. HWi or HEi NW cor. SE cor. HWi of SEi 38 92 50 29 750 314 451 730 200-750 Gravel env . 168-180, 280-303 214-262, 295-434' 31 45 '56 8 '83 82 2.6 1.8 0.6 1-5 2.0 70 1 100P 100F 8-23-38 9-12-38 9-13-38 4-19-38 12-27-37 77 72 78 7.9 8.2 8.6 7-9 7-8 818 316 1080 302 296 0.07 0.03 0.10 0.04 0.04 63 28 65 40 31 2.24 1.73 0.97 1.40 I.69 0.78 0.63 0,43 0.52 0.45 5.22 0.92 8.28 1.27 0.94 0.00 0.56 Tr! I.69 2.44 1.78 2.45 5.01 0.5 1 * 5.72 0.32 1.56 0.25 1.75 0.25 0.00 0.02 0.03 0.05 NWi of NWi 14 -17 -18 -10 556 1224 1390 400 516-554 '22 29 53 62 '72 102 0.5 i!2 2.2 2-9 iiid. 120P 120P 10-13-34 3-20-38 7-29-38 8-23-38 9-16-37 70 73 73 7-7 8.4 8.1 8.1 321 319 277 293 847 0.04 0.03 Tr . 0.03 0.09 28 31 71 46 29 1.71 1.80 0.70 1.07 5.05 0.68 O.78 0.04 0.49 1.01 0.93 1.17 1.78 1.31 2-53 o!6o 0.34 Tr. 0.30 2.66 2.83 1.37 2.13 2.17 0.35 0.44 0.55 o.to 3.32 0.34 0.35 0.43 0.60 2.45 0.02 0.04 0.03 0.00 o.o4 Nr. NW cor. HEi of SWi SW cor. HWi HW cor. SEi 1062-1104, 1140-1206 611-13,645-47,1010-1150 108-326 5-7- 28a 5-7- 28b 5-7-280 5-7-30 5-?- 31a 130C HW of SE cor. or HEi 700' 1 HE of ctr. sec. 200'S, l620'E or ctr. see. HE cor NWi NWi or SEi of HEi 32 38 33 72 9 660 646 243 222 178 524-534,549-552,582-636 510-540, 567-638 85-103, 151-162, 198-228 77-126, 140-192 110-178 58 64 77 66 70 75 72 9 S 88 87 1.5 0.9 0.5 1.0 0.8 41P 41P 12 28P 50P 9-13-38 9-26-38 8-4-38 7-19-38 7-19-38 69 69 74 75 73 8.2 7.9 8.0 8.0 7-7 310 295 408 493 921 0.13 0.03 0.05 Tr. 0.02 32 32 34 39 33 1.56 1.60 2.28 2.31 5.27 O.65 0.49 0.58 0.57 1.08 1.05 0.97 1.46 1.89 3-15 Tr, 0.00 Tr. 0.00 0.00 2.63 2.42 3.12 2.47 3.62 0.31 0.4o 0.53 1.38 3.67 0.29 0.21 0.50 1.00 1.59 0.04 Tr. 0.07 0.13 0.75 5-7- 31b 5-7-35 5-8- 31a 5-6-31b 6-6-1 NW cor. SEi Nr. SE cor. SWi of HWi Ctr. W aide, NEi or HEi Adjacent to 5-8- 31a SW cor. SEi or SWi of NEi 12 -50 -50 46 300 300 328 1026 296 90-154, 200-232, 251-288 150-300 93-96, 185-201, 272-316 1013-1026 205-296 '96 27 '78 iio "82 1.2 i.o 0.2 0.8 50F 70 20 11 7-19-38 12-21-38 9-13-38 9-13-38 7-19-38 73 72 73 82 6.1 8.2 8.2 8.2 8.3 354 312 304 280 307 0.02 6!o2 Tr. 0.05 39 39 43 59 70 1.87 1.70 1.39 0.75 O.72 0.35 0.43 0.38 0.39 0.11 1.39 1.3* 1.33 1.64 1.95 0.00 *Tr. Tr. 0.21 2.34 2.32 2.42 1.88 1.24 0.39 0.65 0.41 0.46 O.52 0.51 0.30 0.31 0.39 1.10 0.11 0.04 O.OC 0.02 0.02 6- 7- la 6-7-lb 6- 7- 4a 6- 7- 1b 6- 7- 13a Ctr. N aide, NWi or NEi 310' W, 720'S or ctr. H aide 900'W of NE cor. or HWi Hr. ctr. NWi of HEi Hr. NE cor. SEi of HWi -40 -42 31 24 -63 325 300 189 134 205 200-325 120-300 91-92. 94-96, 97-111 66-78,112-115,124-144 38 78 54 54 0.8 0.9 1.0 1.0 0.8 41P 41 P 49P 49P 10 7-18-38 1-13-39 7-18-38 7-15-38 7-18-38 72 72 70 73 72 8.4 7.8 7.6 8.0 8.5 322 287 262 290 263 Tr. 0.03 Tr. 0.03 31 37 36 42 42 1-93 1.59 1.46 1.58 1.28 0.32 0.27 0.25 0.19 0,20 1.03 l.ll 0.95 1.26 1.06 Tr. 6.00 Tr. 0.08 2!22 1.88 1.92 1.82 0.5B 0.38 0.44 0.56 0.35 0.46 0.34 0.32 0.39 0.29 0.06 0.12 O.05 0.07 0.05 6- 7- 13b 6-7-17 6-7-23a 6-7- 23b lOC'SE from HW cor. NEi HW cor. SEi of SEi NE cor. SWi of SWJ Hr. HW cor. NEi of NWi '-5 -64 130 350 632 1263 79 '94 58 40 0.8 0.9 2-3 1.0 130P 240P 40 27 34 '8 8-21-41 9-6 -38 7-18-38 11-27-40 11-27-40 1- 7-19 1- 8-30 9- 6-38 7-19-38 7-13-38 75 72 76 73 8.1 8.0 8.1 8.3 1540 266 1270 256 262 242 271 361 272 0.10 Tr. 0.15 0.04 0.07 6!o2 0.20 Tr. 0.07 46 19 50 75 53 61 77 74 59 58 7.12 0.99 5-15 0.58 I.07 0.75 0.54 0.64 1.27 1.09 1.18 0.52 0.82 0.13 0.16 0.25 o.oc 0.26 0.13 7.00 1.46 6.01 2.10 1.38 1.57 1.85 1.80 2.09 1.66 Tr. 0.00 0.00 0.10 0.00 "Tr. Tr. Tr. 2.05 1 94 2.07 1.69 1.99 1.75 1.65 1.69 I.96 1.75 7.60 0.21 5-13 0.37 0.40 0.40 0.34 0.39 0.67 0.48 5-75 O.63 4.91 0.30 0.25 0-34 0.40 0.40 0.97 0.56 0.06 0.00 0.20 0.04 0.03 o!6o 0.01 0.02 325-350 120-632 Gravel env. 836-1263 6-7-24 6-7-21 6-7-24 6-7-25 6-6-5 Ctr. W aide, HWi of HEi -77 -85 -81 1414 218 640 966-1170, 1260-1402 31 30 '60 4o 1.2 0^2 0.6 90CE or NW cor. SWi HW cor. SEi of SEi 62-68, 112-124 206-306, 540-640 6-8- 6a 6-8-6b 6-8-10 6-6-lla 6-8-llb 200'E of NW cor. HW cor. SEJ of 3W t NW cor. swf or SEi NW cor. swi or swii HW cor. E$ of SWi of SWi -44 -58 -105 -109 -107 113 540 525 640 400 100-113 490-540 110-525 Gravel env. 610-640 90-400 Gravel env. 34 12 8 56 29 45 0.6 1.0 1.1 0.5 20 16 22 15 19 9-27- 38 9-27-38 10-19-34 9-13-38 9-13-36 74 72 75 7.8 7.9 7.9 435 287 302 486 0.07 0.04 6!o3 0.10 30 41 "5 62 85 2.60 1.38 O.65 0.88 0.65 0.50 0.25 1.47 0.24 Tr. 1.31 1.32 1.74 I.83 3.62 0.00 0.00 0.00 0.00 Tr. 2.49 2.15 1.80 1.83 2.17 1.01 0.50 1.75 0.81 1.48 0.80 0.25 0.3? 0.34 O.69 0.02 0.04 Tr! 6-8-17 6-e-20 6-8-21 6-8-24 6-6-25 Nr. ctr. HEi In NEi NW cor. SE cor. SWi of SEi SW cor. Nj of HWi -113 -103 -132 140 1020 517 1245 724 50 22 56 33 '72 156 71 0.1 1.5 0.2 0.6 3.1 20 256P 8-23-40 7-15-43 9-27-38 6-17-32 6-15-32 73 80 78 i' 9 8.2 274 251 in 429 0.05 0.01 0.01 0.06 0.06 50 63 53 86 64 1.16 0.84 1.13 0.30 0.94 0.17 0.06 0.15 0.07 0.39 1.31 1.52 1.44 2.19 2.36 Tr. 0.00 Tr. 1.91 1.69 1.90 1.55 1.25 0.43 0.46 o.4i 0.70 1.56 0.25 0.25 0.35 0.30 0.90 0.03 0.03 0.01 0.01 Tr. 217- 760-1245 72-603 6-6-25 6-8-28 6-8-30 6-8- 32b 6-8-36 In SEi 600 'W of NE cor. NWi HW cor. SEi of SE i HW cor. SWi -162 -136 -155 720 108 1025 1880 220- 85-108 1000-1025 1540-1880 Flowing Flowing i'.5 0.5 l.o 0.2 25P 52P 7-19-38 7-15-43 7-19-38 9-27-38 12-9 -36 76 72 81 8.6 8.9 7.7 8.8 7.7 504 249 2490 224 246 0.07 Tr. 0.08 0.06 o.oe 72 62 40 91 1.29 0.87 12.50 0.20 0.46 0.12 0.06 2.52 Tr. 1.03 3-56 1.49 10.19 1.94 1.16 0.46 0.20 0.00 0.88 1.20 1.44 3.16 0.60 1.64 I.9I 0.49 10.70 0.36 0.54 1.36 0.26 11.45 0.28 0.40 O.OC 0.03 0.30 0.03 0.02 7- 8- 2a 7- 8- 2b 7-8- 2c 7-6-4a 7-8- lb In Ej or NEi of NEi 400' W of HE cor. Nr. NW cor. 200 'E of NW cor. NEi HW ccr. SEi -162 -161 -160 -152 -155 500 600 452 912 Flowing Flowing Flowing -23 0.5 0.1 0.1 12 Past. 12- -33 9-13-38 11-25-38 9-27-38 9-27-38 75 73 6\6 .6.3 8.1 8.5 239 246 242 254 Tr'. 0.22 0.02 0.05 74 79 66 it 0.55 0.48 0.75 0.63 0.35 0.16 Tr. 0.10 0.11 0.03 I.96 1.77 1.62 1.61 2.05 0.10 0.62 0.04 Tr. 0.25 1.46 0.79 1.51 1.58 1.29 0.77 0.51 0.66 0.47 O.52 0.37 0.36 0.31 0.28 0-39 6!6c 0.06 0.04 0.03 500-600 440-452 550-890, 696-912 7-8-7a 7-6-7b 7-8-7C 7-6-12 7-6-16 200' H Of 3W cor. SEi of SEi Hr. SE cor. 185' NW of 7-8- 7b 850' W of ctr. see. Hr. HW cor. SEi -90 -90 -90 -183 -126 618 225 312 568 600 300-618 185-225 110-118,248-253,274-288 476-486, 555-568 490-525 64 Plowing 26 91 1.3 0.1 1.1 39 5' 12-29-37 4-30-32 9-13-38 9-12-38 7-29-38 78 73 75 8.0 8!2 8.1 8.5 230 233 245 240 0.03 6!o2 0.03 0.02 86 ?i 87 80 o.i6 O.36 0.46 O.-O 0.33 0.10 0.05 Tr. Tr. 0.09 2.01 I.98 1.67 1.92 1.71 0.20 Tr. Tr. 0.42 1I32 0.86 1-39 0.95 0.45 0.43 O.52 0.53 0.50 0.30 0.68 0.51 0.34 0.43 0.02 6.00 0.00 0.03 7-e- 31a 7-8- 31b 7-8-3lc 7-8- 35a 7-8- 35b 900 '3, 300 'E of HW cor. SEi 128o'W, 520'S of NE cor. Nr. SE. cor. NEi of HEi Ctr. SJ, SEi of HWi NW cor. 3 J of 3Ei or HWi -85 -102 -122 -158 -147 895 1013 250 900 1180 300-895 Gravel env. 06-96,450-56,620-38,910-101: 82-S7, 173-215, 310-900 175-1180 73 47 2 10 64 85 20 28 1-7 0.8 o.'e 0.6 74 48 10 ' 40 7-18-38 7-18-38 7-18-38 2-18-37 4-20-37 94 95 86 96 96 9.4 9.6 9.2 8.3 8.6 351 314 256 301 340 0.07 0.10 0.05 0.10 0.07 87 93 V II 0.45 0^62 0.20 0.32 Tr. Tr. Tr. 0.16 0.09 2.92 2.67 2.06 2.61 2.96 0.72 1.01 O.76 0.45 1.02 0.60 0.51 0.86 1.36 0.62 1.07 0.70 0.5? 0.9I 0.96 0.93 O.50 0.40 0.65 0.65 Tr. 0.00 0.01 0.02 0.01 7-6- 35f 7-9-8 7-9-16 7-9-17 7-9-21 Ctr. Sj, SWi or NWi Kr. SW cor. (W of tracli) 100'S of HW cor. NWj or SWi 700'S or NW cor. NE* H or hwy. Hr. SE cor. NEi -192 -189 -194 1015 1511 916 880 603 600-1015 1410-1485 20 Plowing Plowing 35 57 0.5 0-3 0.6 40 25' 15 9-26-43 7-29-38 11- 7_40 9-12-38 9-12-38 81 78 6.9 8.6 299 322 315 253 461 0.15 0.07 0.08 0.05 0.15 p 67 0.10 0.35 O.10 0.25 1.41 0.01 0.06 Tr. Tr. Tr. 2.73 2.67 3.03 2.00 2.92 0.89 0.55 0.31 1.35 0.25 0.74 0.46 1.64 0.15 1.46 0.75 1.76 0.78 0.58 2.39 0.42 0.49 0.20 0.36 0.40 Tr. 0.03 Tr. 0.00 O.OC 800-880 300-603 7-9-22a 7- 9- 22b 7-9-25 7-9-27 7-9-29 -7-y-36 Hr. HE cor. SWi of SWi 10' H of 7-9-22a Ctr. N aide, HWi or HWi of SWi HE cor. SWi 300' SE of NW cor. 300' SW of KE cor. -199 -199 -21.9 -217 600 412 600 651 610 40C-412, 560-570, 590-600 35O±-360±, 400-412 480-600 600-651 290-610 Gravel env. Plowing 8 Plows Plowing 32 25 30 0.2 0.2 1.2 7 IOC Ponds 9-27-38 9-27-38 4- 3-39 9-12-38 9-12-38 79 81 76 9.1 7.9 9.0 254 1710 665 387 254 0.03 0.10 0.14 Tr. 0.05 89 61 94 91 90 61 0.24 5.34 0.33 0.21 0.25 4.43 0.02 1.37 0.06 Tr. Tr. 0.29 2.17 10.56 6.00 3.36 2.17 7.46 1.14 0.00 0.61 0.84 1.47 0.41 0.17 1.56 1.72 1.48 0.05 1.43 0.77 15.22 1.53 1.00 0.61 9.46 0.30 0.63 2.0$ 0.33 0.3 1 * 0.67 0.00 0.00 0.01 0.01 0.00 0.01 r-'--la 8- 8- lb 8-8-4a 8-e-lla SW cor. 3Ei of SWi Hr. Ctr. N aide, SEi or HWi 900'S, 1000'W or HE cor. Ctr. HEi or NWi' -185 -195 -14 -135 325 789 430 860 350-789 200-430 740-777,797-820,860 Plow Flowing 138 12 143 47 1.0 0.5 2.9 0.8 40 30CP 125 46 12-28-37 12-10-38 2-18-37 7-14-38 2 9 80 100 103 8.5 8.6 8.0 9.5 370 306 726 362 0.14 0.15 0.05 0.23 90 93 70 95 0.19 0.19 1.47 0.18 0.17 0.13 0.65 Tr. 3:08 2.78 5.00 3.21 0.14 0.00 1.31 1.01 1.51 1.58 0.02 1.5? 0.92 2.12 1.27 0.32 3-54 0.64 . 0.02 0.05 0.01 8- 8- lib 8-8-13a e-6-13b 8- 8- 13c 8-e-l4 Ctr.S side. Hi or SWi of HEi Ctr. N£ or NWi Hr. ctr. SEi or HWi 600' SE or ctr. sec. 300 'N of SW cor. NEi of NEi -148 -159 -156 -150 -134 561 960 824 818 340 519-561 742-952 700-824 706-800 Prob. 280-340 15 15 10 25 18 30 49 30 41 36 0.4 2!4 0.6 0.8 20 55P 73 32 40 11- 9-35 2-23-37 6-15-38 6-15-38 2-18-37 94 100 106 104 92 6.6 8.5 5-5 8.2 328 398 426 699 310 0.11 0.22 0.27 0.30 0.08 96 93 95 90 90 0.12 0.15 0.15 0.48 0.16 Tr. 0.14 0.04 0.16 0.17 2.88 3.68 3.90 5.48 2.94 0.99 1.02 0.72 0.34 0.23 0.59 0.96 1.26 1.09 1.52 1.02 0.90 1.01 1.49 1.07 0.43 0.90 1.13 3.38 0.70 O.OC Tr. 0.00 Tr. 0.01 8-6- 24a 8-8-24d 8-9-29 6-9-33a 8- 9- 33b 300' 3 of NW cor HEi or NEi Hr. NW cor. SEi of HEi Ctr. W aide, SWi of NWi 300'S of HW cor. Nr. ctr. NEi or NWi -155 -150 -174 -191 910 605 690 350 800-900 15 Flow "6 30 20 39 31 25 2.5 0.3 1.1 1.4 0.5 59P 28 40 20 7-18-38 11- 7-40 10-21-38 5-25 37 5-25-37 109 9 I 106 lie 95 9.0 U 6o4 1390 675 1740 2170 0.28 0.41 0.48 0.71 0.79 91 67 93 85 86 0.38 4.47 0.45 2.14 2-33 Tr. Tr. 0.06 0.57 5.09 9.07 5-38 12.67 17.43 0.68 0.00 0.54 0.00 0.45 0.60 0.51 0.47 1.02 1.47 1.33 10.64 1.48 1.80 6.30 2.76 2.46 3-39 12.04 11.92 0.03 Tr. 0.03 0.14 0.11 580-690 200-350 8- 9- 33c 8-9- 33d 8-9-33e 8-9-338 8-11-10 NW cor. SWi or NWi of HEi Ctr. W aide, SEi or NWi Ctr. W aide, Si of NEi Nr. ctr. NEi or HWi -202 -176 -192 197 I 16 865 180 97 167-197 144-150, 159-169 703-836 130- IBO Flowing 30 0.5 0.2 0.3 35P 41P 41P 9-13-38 9-13-38 9-13-38 11- 7-40 5- 3-38 88 99 119 90 82 8.6 '•8 7-8 K9 666 3720 606O 34 66' 0.05 0.27 0.35 2!go 93 82 79 78 0.41 3.82 10.92 3.69 Tr. 2.20 1.87 3.40 5.35 27.01 42.65 24.60 0.58 Tr. 0.00 0.20 1.51 1.16 0.76 3-17 2.75 8.86 6.39 3.96 22! 87 48.00 24.30 0.00 0.05 °. .19 0.01 To conv ert E. P. M. to parts per nllUo a (p.p.m ) oulti ly by factor indicated 20.0 12.2 23-0 30.0 61.0 48.0 35-5 62.0 DESCRIP TIOH * CERTAI H DATA B { COLUMNS Column L: Flrat number la township sou th of Sax Be mart lno Base; aecond number Is re two or more veils In one se nge east tion. or San Bernarc ilan; third number ion. Letter follow 3 Elevation of ground surface Ho. 1. For other wells, el at veil 1 n feet pproximated Trom U. S. Bureai d rrom U.S.G.S. and County ma or Reels pa (cento matlon maps (c ontour 1 LOO rt.) iterval . 2 Minus alg ft.) ft n indie ates el within laproi ovation below ement Dl 1. 6 Minus sign indicates water u nder pre sure. 9 "Ind." refers to railroad In duatrlal use, "Do m." to domestic use, "F" lndlc ates othe v wall a also. Bed to i rrigate acr age she 12 Determined with glass electrode pH meter 14 "Tr." ia leas than 0.01 p.p.m. 15 Per cent sodium aa of total cations. 16-23 m-e./l . ml 111 -equivalents per liter. 16-22 "Trl' Is leas than 0.04 m.e,/l. 23 "Tr." 1b less than 0.01 m.e./l. )te: 34 analyses courtesy Rubidoux Laboratory, Bui (except early records). l of Plant Industry, U.S.D.A., Riverside, California. Also 1 privately made. I § co K W Eh g . P W >H S -P CM a3 HOJ(\J H i-H^h- rH CVI 00 U M it o 1 -H -H -H HH -H -H -H -H -H CM LT\IT\ m CO CVI onoo cm NN-00 i>- 00 O N00 o Eh H rH o on MO OC0C0 H MO CM MO-* O n o MO t- LH on H rH t-CAH -p -H -H -H -H -H -H -H -H -H p o -P 0) O -.=*■ -H <*n O On MO CO CO C- OACM -3-^r on ■p p pq ^" LP\t- CVJ invo minm a P Jh CO o LA \ o o o O o o CO o o\ O -H CVI to r-i CM rH in -=T CM H OVC0 •H -P O P t> -P % -H-H -H -H -» -H -H. -H -fl +-> 3 03 O TD o o o o o o o o o o P >i p moo CM C--MO -3- co in HOP a rnroro t- NMO in on on W O -H •H a rH rH CVJ to ■H H o mo on^j- (J\ cm in co in in (D PhTJ iH cvj on r-i cm on rH cm on t>a O HriH CVI cm cm on on on Eh O O O o o o H o o o in O O O O o H o int-o -P in NO o t--o o t- i>- Ph in N -p o o rH o o o P -P -P P o -p -P Ph > O -P Ph o in O -p -P O H > O rH > rH > 03 !» m o i>» in o >> o in o t* -p ■H a a a -p •H a a a -P •H a a a Oh > 3 3 3 > 3 3 3 > 3 3 3 O ■H ■H-Hrl ■H tH •H -H ■H •rirl-H -P t3 ■P t3 -P T3 ■d X) +-> t3 "O TJ o o o o O o o o O O O O ft 3 to m to P to m m P to to m T3 T3 T3 Eh o o >R^\R P o o >2R •SO& P O o ^.■^•^ TABLE 5 ANALYSES OF 1-1 AQUEOUS EXTRACTS OF VIRGIN AND CULTIVATED SOILS IN AREA OF LOW MAGNESIUM CONTENT Plot Sample Depth Electrical Conductivity at 25° C pH Ca++ Mg""" Na + K + HC0 3 " S V~ Cl- NO3- no . 1 feet 0-2 2-4 4-6 mlcromhos/cm 18180 5850 2320 7-7 8.1 8.1 m.e ./l 13-7 1.1 0.4 m . e . /I m.e ./l 190 53-8 19.7 m . e . /I 3.4 2.1 1.1 m . e . /l 3-1 1.8 1.9 m.e ./l 117 30.3 11.9 in, e ./l 84.0 25.5 8.0 m . e . /l 2.6 0.6 0.3 2.6 0.5 0.2 la 0-2 2-4 4-6 368 369 296 7.8 8.0 8.2 0.7 0.4 0.3 0.3 0.3 2.8 2.6 1.3 0.9 0.9 0.9 1.4 1.9 1.4 1.2 1.0 0.5 0.9 1.0 0.7 0.5 0.2 0.2 2 0-2 2-4 4-6 8770 4200 3170 7.1 7.0 7.2 36.6 12.1 5-7 10.5 t-9 3.4 46.3 27.2 19.9 3.3 1.4 1.0 0.8 0.8 0.7 29.1 9-8 4.5 67.8 34.6 24.1 0.5 0.5 0.3 2a 0-2 2-4 4-6 270 549 1230 8.0 7.9 7.7 0.5 0.3 1.7 0.1 0.1 0.2 1.9 4.1 7.9 0.9 0.1 0.2 1.7 1.9 1.5 0.7 1.8 5.6 0.7 1.7 4.0 0.1 0.1 0.3 ( Plot 1, Virgin soil; la, soil from adjacent citrus orchard (Sec. 13, T8S . R8E) Plot 2, Virgin soil; 2a " " adjacent vineyard (Sec. 34, T7S . R8E) Low magnesium waters and soils As mentioned previously, ground waters in Coachella Valley are generally low in magnes- ium. This is especially true of the western portion of the lower part of the Valley. Stud- ies made on the water soluble and replaceable magnesium present in samples of soil collected from cultivated and virgin fields revealed a very low magnesium content. These data are re- ported in Table 5. It is indicated that the cultivated fields have a lower content than the adjacent virgin soil. Analysis of leaves from a citrus orchard and vineyard showed a lower magnesium content than leaves from plant- ings on soils higher in magnesium. While these data do not prove that crop yields are affected by the low magnesium con- tent, they are reported as factual information regarding soil and water conditions. The sup- plemental water supply which is to be brought to the Valley is relatively high in magnesium. GR0UT-1D WATER LEVELS The Coachella Valley County Water District made available data on ground water levels which they have collected more or less continuously since 1919 . These wells have been located and their approximate ground surface elevations ob- tained from the 2-foot contour maps of the U.S. Bureau of Reclamation. Level surveys have been made to most of those wells located beyond the boundary of the area mapped by the Bureau of Reclamation. Information on well depths and depths of perforations was obtained wherever possible . At first, all observations were made on ir- rigation or domestic wells, but in 1927 3 a num- ber of perforated cased wells, 15' to 30' in depth, were installed. These are in the trough of the Valley where the water table is relative- ly near the ground surface. Because of the im- pervious nature of some soil strata, and because of the pressure losses In any water moving up- ward, the level of these shallow wells is con- siderably below that of the deeper wells. In fact, with adjacent irrigation wells in the lower trough of the Valley it is usually found that the static pressure increases with the depth of the well. A selected list of wells measured by the Dis- trict is found in Table 6. This table does not include a number of wells measured in the 1920 to 1927 period but since lost, and other wells of which measurements were discontinued before any significant records were obtained. All wells measured from I927 to 1939 are included. Table 7 gives a selected list of observations for the wells listed In Table 6. The readings selected are 3 to 5 years apart, and are taken for that period of the year when irrigation de- mands are least (January or February) . The elevations of the water table as of Jan- uary, 1939 > are shown on Figure 1. Shown also are the approximate limits of flowing wells at tha.t time. Two abandoned wells, which may be partially plugged or relatively shallow, are omitted from the data from which ground water contours were located. These wells are Nos. 4-7-31 and 7-9-7b. Twenty-one representative wells scattered over the Valley were selected on the basis of continuity of record and geographical position, and all records available for these were plotted as shown in Figure 3, (page 26) Since irrigation is normally a summer opera- tion, ground water basins are usually not af- fected by pumping during the winter months . Water levels then reflect the natural regime of the ground water except as modified by pre- vious withdrawals of temporarily "stored ' water. If the basin is not artesian, and the average specific yield of the soils is known, any change in water level from one winter to another can be used to estimate quantitatively the change in storage. If the basin Is artesian, changes in levels from one winter to another may indi- cate only a change in pressure. Such changes in pressure would be caused by certain changes in storage over only a part of the basin. The differentiation between actual storage loss or gain and change In pressure is at best only a guess . In Coachella Valley the ground water is ar- tesian in nature, and considerable pumping is done through the winter months. During the winter water is now pumped at about one-fourth the summer rate. Winter pumping, however, is becoming more common because of the increasing acreage of crops such as dates and grapefruit which are irrigated the year around, and be- cause of the decrease In the last 20 years of such crops as cotton and onions, which are not planted until early Spring. Further, there has been a stea.dy increase in the cropped acreage in the Valley, so that ground water withdrawals have become greater. It should be obvious, therefore, that the continued drop in water levels in Coachella Valley has been primarily a reflection of increased use, and not neces- 10 TABLE 6 DESCRIPTION OF WELLS MEASURED FOR STATIC WATER LEVELS BY COACHELLA VALLEY COUNTY WATER DISTRICT C .V C. W.D. Location In Sec- tion indicated Depth of Well Reference Point (R.P.) Well Elev . Above Ground Description 1 p 3 4 5 6 7 no . no. "DEEP" WELLS 3-5-28 4-5-29 4-6-8 4-6-18 4-6-19 4-6-27 4-6-30 717 hi o 716 644 328 715 645 Nr.NE cor. NW of NW 4-7- 31a, b 641 4-7-32 640 5-5-2 5-5-12 659 648 5-6-6 5-6-l8a 647 649 5-6-l8b 719 5-6-21d 5-6-22f 347 658 5-6-36 5-7-4 5-7-8 5-7-10 5-7-13a 5-7-13b 5-7-18 5-7-20a 5- 7- 20b 5-7-22b 5- 7- 26b 5-7- 30b 5-7- 34c 6-7-8a 6- 7- 8b 6-7-16 6-7-20 6-7-22 6-8-2 6-8-5 6-8- lib 6-8-19a 6- 8- 19b 6-8-21 6-8-23a 6- 8- 2 3b 6-8- 32a 6-8- 32b 6-8-36 7-7-1 7-7-3 651 639 642 638 637 Old 656 655 654 Old 652 634 636 635 Old 631 630 713 721 620 628 626 378 619 712 708 707 706 622 623 NW cor. of SE f Ctr. of section 400' W & 1820'S of ctr. sec. In NE i 300' E & 1300' N of SW cor. 2500 ' W & 130C S of NE cor. 530' E & 2640' N of SW cor. Nr. NW cor. of SE £ of NW £ Nr. SW cor. of NW £ of SE £ Nr. ctr. of N \ of SE i 200' E & 500 ' N of SW cor. 435' E & 220 'N of SW cor. of NW 55' E & 82'S of SW cor. of NW £ of SE £ SW £ of SW £ of NE i 100' E & 530' N of SW cor. of SE £ 800 ' W & 375' N of SE cor. of NE £ of SW £ 1750' W & 10 'S of NE cor. 1130 'W & 380 'S of NE cor. of SE i 2110' W & 1300' N of SE cor. of NE £ 530 'E & 790 'S of NW cor. feet feet ... +651.7 . . . +324.6 ... +383.1 400 +231.6 . . . +212.6 1134 +164. . . . +284.5 . . . +117. ... + 86.0 240 +245.2 . . . +224.0 47 24 SE i Nr.NW cor. of SW £ of SW £ 2640' E & 1321 'S of NW cor. 300' E & 450' N of SW cor. SE £ of NW } At SE cor. of SW £ 950' E & 4l0'S of ctr. sec. 1210' W & 2530' N of SE cor. 3860 ' W & 50 'S of NE cor. NW £ of NW i 95 SW i of SW J 140' W & 60' S of NE cor. 2150 ' W & 170 'S of NE cor.' 1270 'E & 2610 ' N of SW cor. 1200' W & 1180 ' N of SE cor. 690'E & 120C N of SW cor. 300' E & 120S of NW cor. 1110' W & 1905' N of SE cor. NW cor. 670 ' E & 70 'S of NW cor. 340 'W & 960 'N of SE cor. 1160 'W & 1260 'N of SE cor. 1260 'W & 1220 'N of SE cor. 100 'E & 2500 'N of SW cor. Nr. NW cor. of NE £ 600 ' W & 660 'S of NE cor. . . . +212.9 330 +190.4 206 + 47.7 ... +47. ... +54. ... +23. ... -10. 600 -20.7 140 +149.3 ... + 9^ • 3 ... + 84.9 183 + 11- 704 - 10.8 116 + 60. 114 + 26.5 ... +26. 123 + 23.3 ... - 19.1 ... -10. 1530 -42\ 640 400 1415 -56. ■ 80. •104. ■ 84. . . . -110.6 517 -107. . . . -121. ... -113. . . . -134. 1025 -132. 1880 -151. ... -113. ... - 71. feet 0.0 1.2 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.7 +224.0 0.6 +228.2 -5.5 0.2 0.4 302 +183.7 0.7 0.5 0.0 0.0 0.0 1.5 0.0 1.7 0.0 3.6 1.7 0.0 0.0 2.2 0.8 0.6 0.0 0.0 0.0 1.0 2.0 0.0 0.5 6.1 1.0 0.0 2.0 4.0 2.2 0.2 1.1 11 Top concrete base Bottom of pump base Hole in pump base Abandoned Bottom pump base Top casing. Abandoned Top 12" casing. Abandoned Abandoned Top casing Top casing in pit Abandoned Cone. edge pit. 3-9' above top casing. Abandoned Top casing. Abandoned Remove plug. Meas . in disch. pipe Cone, floor Abandoned Top casing. Abandoned Top cone, curb on N. Top 2" casing. Abandoned Top casing Top casing Top casing Top casing. Abandoned Cone, floor. Abandoned sanded to 600 ' . Top wood clamp on casing, Top casing Stud bolt Top casing Top casing Bottom pump base Hole in pump Top of bushing in top 6" T. Faucet - SE cor house At £■ - \ reducer 1.2' above ground Faucet on N. side house At outlet valve . Abandoned (continued on next page) TABLE 6 (Continued) DESCRIPTION OF WELLS MEASURED FOR STATIC WATER LEVELS BY COACHELLA VALLEY COUNTY WATER DISTRICT C .V.C . W.D. Location in Sec- tion indicated Depth of Well Reference Point (R.P.) Well Elev. Atove Ground Description 1 2 3 4 5 6 7 no . no . "DEEP" WELLS ( Continued] feet feet Nr. NW cor. Nr. SE cor. 770' W & 730'S of NE cor. 1340 'E & 370'S of NW cor. 1280 'W & 1660'S of NE cor. 450'E & 930'S of ctr. sec. 830 'E & 340 'N of ctr. sec. 2370'E & 360 'N of SW cor. of NW i 2000'E & 270 'N of SW cor. 2530 'E & 1480 'N of SW cor. 1710'E & 1540'S of NW cor. Nr . SW cor. 2640 "E & 240'S of NW cor. 1580 'W & 660 'N of SE cor. of NE i 90'E & 40'S of NW cor. of SW i 400'E & 270' S of NW cor. of SW i 1050 'W & 110'S of NE cor. 2110 'W & 690' S of NE cor. 1340 'W & 280'S of NE cor. 80 'W & 80'S of ctr. sec. 8-9-33f 609 50'E & 260 'N of SW cor. SHALLOW GROUND WATER WELLS : 6-8-4A 57 NE cor. 6-8- 16A 4 5'W & 34'N of SE cor. 7-8-3 621 7-8-7d 601 7-8-17 602 7-8-18 705 7-8-21 610 7-8- 34a 603 7-8- 34d 606 7-8-35c 604 7-8- 35d 704 7-8- 35e 70 3 7-9-7 615 7-9-8 374 7-9-20 613 7-9-26 711 7-9-30 614 7-9-33 710 8- 8- 4b 702 8- 8- lie 607 8-8-24b 701 8-8-24c 700 6-8-18A 6-8-20A 6-8-21A 6-8-25A 6-8-26A 6-8- 32A 6-8-33Aa 6-8-33Ab 6-8- 34A 6-8- 3 6A 7-8-2A 7-8- 8A 7-8-lOAa 7-8-lOAb 7-8-11A 7-8-23A 7-8-35A 7-9-l8Aa 7-9-18AD 7-9-20A 7-9-22A 7-9-27A 7-9-33A 7-9-36A 8-8-13A 8-9-7A 8-9-20A 2 3 7 14 8 9 10 11 12 18 22 20 21 25 26 30 38 27 28 33 37 42 45 46 51 47 54 30 32 28 30 50 35 22 43 2 r SW 27 30 2 1 : 74 40 54 32 W & 32' N of SE cor. E & 230'S of NW cor. W & 32'N of SE cor. E & 40'N of SW cor. NE of SP on N sec. line E & 18+' S of NW cor. SE of prop cor at NW cor. E & 44 'S of NW cor. NE i : & 8'S of fence at NW cor. cor. W & 20 'N of SE cor- E & 2 *S of NW cor. 1 of NW cor. (Rd. liot ' E) N of SW cor. N of SW cor. W & 28' S of NE cor. W & 30' S of NE cor. 42'E & 34'S of NW cor. 43'W & 37'S of NE cor. 2'SE of fence cor. at NW cor. 40'NE of SW cor 25' NE fence l'W of SE cor. At NW cor. of SW £ 2'S of NW cor. At NE cor. 60 'E & 27 'S of NW ccr. 1100'E & 300 'S of NN cor. SW { -154. 0.0 196 - 90. 0.3 1100 -115. 0.6 770 - 71. 2.0 - 91- 0.0 895 - 85. 0.0 - 91. 0.0 410 -152. 6.5 -151. 0.0 1284 -161. 0.0 -185. 0.7 I5ii -192. 500 -206. 2.0 -199. 0.0 -215. 0.0 -233. 1.0 - 12. -1.0 950 -149. 1.0 910 -155. 0.0 -110. 0.6 20.9 31.5 31.1 23.0 32.0 30.9 30.6 25.5 11.0 17.0 22. 18.8 25.5 25.6 17.8 22.0 17.0 22.0 18.5 20.3 •133. ■ 83.6 -120. ■ 97. ■111.8 •133-8 ■147- -136. ■116. ■136. • 142. •145. ■160.7 ■174. ■136.7 ■ 164. ■ 166. ■180.3 ■194.6 ■189.9 ■192.0 •193. •207.1 •209.6 ■225.0 ... -234. 20.1 -218.3 17.2 26.1 12.7 16.0 12.9 15.7 ■206.0 •210.6 ■ 207 Pump base Top reducer on S side Bottom pump base Shut off valve on N. Old well at 2 palms J" cock on top of plu£ Top casing. Abandoned Top 2" pipe in plug Top concrete base 1.0 Pump base at air line Mud at 17' in 1939 Shifted to SW cor. SE £ of SE £ in 1939 0.4 0.3 6^5 0.4 At NW cor sec 21 up to 1933 Nr. NE cor sec 35 to 1939- Surface water enters. 1939 At NE ccr sec 2 (7-8)to 193S R.P. changed. 1927 7 Cleaned out 9-3-38 Destroyed Destroyed. 1938 (concluded on next page) 12 DESCRIPTION OF COLUMNS : Column No. TABLE 6 (concluded) 1. First number Is township south of San Bernardino Base, second number Is range east of S. B. Meridian, third number is section. "A" following designates shallow ground water wells, usually 15 to 25 ft. deep. Lower case letter following differentiates two or more wells in one section. 2. Number used by Coachella Valley County Water District. 3. Location of well In section. 4. Depth of well in feet. 5. Elevation in feet of reference point (R.P.) above (+) or below (-) sea level, U.S.G.S. datum. Elevations shown only to the nearest foot were estimated from U. S. Bureau of Reclamation topographic maps (contour interval = 2 ft.). Figures shown to 1/10 of foot actually determined in field. Elevation of R.P. for well 4-6-8 estimated from Metro- politan Water District of Southern California map H- 339-4. 6. Feet R.P. above average adjacent ground surface as established by Water District in 1939 to correlate with topographic maps. Not always the same as immediate ground surface at well. 7. Description of R.P all top of pipe) . for "deep" wells. Remarks for shallow ground water wells (R.P.'s sarily a reflection on the adequacy of the sup- ply or an indication of any great change in s torage . Inspection of Figure 3 will reveal that an- nual fluctuation of water levels, as well as rate of drop, increases with distance down the Valley. This indicates that the principal ef- fect of ground water withdrawals has been to lower the downstream levels, thereby reducing the natural losses in the lower basin. Not until the period of 1930 to 1935 were the levels at the upper end of the agricultural area af- fected, and the drop in those levels corres- ponded with large-scale developments In the Indian Wells and Edom districts, upstream. Information in the above paragraph might be summarized as follows: 1. Appreciable ground water withdrawals have the long-range effect of lowering the lev- els in all wells downstream from the wells in question . 2. Ground water levels upstream from a well or group of wells are not significantly affect- ed by withdrawals from thoae wells except with- in a limited radius of those wells • 3. The wells at the upstream end of the dev- eloped areas do not reflect annua.l fluctuations in ground water recharge. In regard to the shallow observation wells, no detailed interpretation has been attempted because there is evidence "that at least some of them did not correctly reflect the actual piezo- metric surfaces of the aquifers intercepted. Although the above discussion would indicate that the supply is largely adequate for the area developed up to 1936- 39 , and probably for a greater area, there is an economic question involved. As more land is irrigated and water levels drop, it is necessary to make additional capital outlays in deepening wells, drilling new wells, and installing new pumps. Further, as the pumping lift increases, the cost of pumping increases. There follows a natural tendency to specialize more on crops whose re- turns justify higher water costs, to improve methods so as to cut down on waste of water, and, sometimes, to abandon unprofitable enter- prises, or to seek other water supplies. Also, as wells become closer together, mutual inter- ference magnifies the increase in pumping lift and decrease in yield beyond the arithmetic low- ering of static levels. In an Investigation of irrigation applica- tions , and of water requirements of various crops (ll), it was found to be a common prac- tice of farmers in the area to apply water in excess of crop requirements. Extensive records were obtained of water actually pumped, or taken from flowing wells, for Irrigation of the var- ious crops. By extending the rates of applica- tion so obtained to the Valley as a whole, using the crop survey, it appeared that in the period of 1936-39 total agricultural withdrawals from the ground water approximated 100,000 acre-feet per year, a portion of which is in excess of crop requirements. The excess applications should largely seep back to the water table, but savings would accrue from pumping less wat- er and thus maintaining higher water levels. However, It must be understood that a certain amount of water in excess of crop requirements must always be applied to maintain a reasonably low salt balance, to provide a margin of safety, and to maintain adequate moisture in all parts of a stratified soil. The crop and well survey, and other data (ll), reveal that pumps in the Valley generally have a low load factor. Group or District operation of pumps should therefore result in economies. The "safe yield" of a ground water basin is sometimes computed on the basis of measurements of water entering the basin minus the losses. Thus, run-off from the major streams is measur- ed, and possibly proportional amounts are estim- ated for minor streams with corrections for sur- face run- off carried over the basin. Such es- timates can hardly account for infiltration from streams above the measuring points, or for infiltration directly from precipitation, on any rational basis. Invariably such estimates, even if carefully made, are low. Some measurements of flow have been made on most streams entering Coachella Valley. Their usefulness has two important limitations. First, they represent only periodical gagings, which gagings were not made during flash floods when a great proportion of run- off probably oc- curs. Second, it appears that opportunity for significant amounts of infiltration exists above the points of measurement. 13 TABLE 7 ELEVATION? OF STATIC WATER SURFACE OF WELLS MEASURED BY COACHELLA VALLEY COUNTY WATER DISTRICT (Measurements for period 1920 to 194?, made during month indicated. Measurements made in January and February normally at highest elevation for year and least affected by pumping. U.S.G.S. sea level datum for elevations.) El evation of wate r surface (above or below sea level) Well Jan . Feb. Jan . Jan. Jan. Jan. Jan. Jan. REMARKS 1920 1923 1927 1930 1935 1939 1944 1947 1 2 3 4 5 6 7 8 9 10 no . feet feet feet feet feet feet 585.3 feet 590.0 544.5 3-5-28 598.1 4-5-29 223.0 226.3 226.0* March 1927. Nov. 1918 = 224.6 4-6-8 159-9 155.2 151.1* 121.1 *Nov. 1943. 4-6-18 168.0* 168.9 167.8 170.5 I67.I *Nov. 1920 4-6-19 159.8 161.0 4-6-27 113.4 109^8 4-6-30 157.4 158.4 158.6 159.3 156.0 Nov. 1913 and Nov . 1918 = 154.5 4-7-31a 42.0 41.4 39.7 37.8 4 -7- 31b 36! 6 23^3 4-7-32 58.3* 58.0 55.7 53.3** 51.2 *Apr. 1920, **Feb. 1930 5-5-2 I65.6 166.8 166.9 168.5 158.7 155.0 5-5-12 146.2* 147.1 146.6 147.3 . . *Dec. 1920 5-6-6 142.1* 142.9 142.7 143-9 144.8 138il 131^2 *Dec. 1920 5-6- 18a 139.2 140.5 139-7 141.0 5-6-l8b 141.4 138^7 143^2 5-6- 21d 105.1 5-6-22f 109.9 iio.8 105.3 ioi!7 97*8 93^7 5-6-36 -21.3 -24.2 -34.5 -40.8 -52.3 5-7-4 32.3* 30.8 27.2 28.3 21.5 22.8 *March 1920 . 5-7-8 28.4 27.4 24.6 19.9 18.3 14.1 9.5 4*!8 5-7-10 -5.8 -10.4* -11.0** Caved *March 1930.**Feb. 1935 5-7-13a -7.0 -23.4 -24.2* -30.8 -34.4 -35.1 -45.0 -53.0 *Feb. 1927 5-7-13b Flowing 5-23.7 Flowing Apr. 1905 and Nov. 1918. Sept. 1917 = -23.7 Nov. 1918 = 49.3' 5-7-18 52.8 52.1 49.5 47.7 43.9 5-7-20a 16.8 15.4 11.5 8.7 5-3 6!7 -k'.Q 5-7-20b 14.6 13.1 9-4 3.0* 3.3 -6.1 -14.7 *Feb. 1930 5-7-22b -20.2 -22.0 Sept. 1917 & Nov . 1918 = -20.0' 5-7-26b -58.8 -58.8* *Feb. 1939 5-7-30b '5.8 '4.3 -2.5 -3-9 -8.1 -13.0 5-7- 34c -27.7 -34.5 -38.7 -44.2 -46.7 -52^5 Nov. 1908 = -24.5' 6-7-8a -38.5 -42.0 -46.5 -51.3 -55.6 -65.3 6- 7- 8b -34.3 -36.2 Apr. 1905 = -24.7' 6-7-16 -77-7 . . 6-7-20 -64.6 -68.7 -73.7 -76.9 -80.6 -84.5 Caved 6-7-22 -48.0 -48.6 -50.6 -52.9 -56.3 -61.0 -62.3 -69*9 6-8-2 -107.3 -110.7 6-8-5 -108i3 -111." 8 9-30-38=-120.0' 6-8- lib -lii.o 115.6 -118.2 -123.0 -127.5 -136.5 6-8-19a -61.1 -66.8 -66.4 -73-3 Flowing Flowing -83.6 6-8-19b -87.5 -77.1 -97.1 -101.0 -101.4 -105.6 6-8-21 -98.9 -100.2 6-8-23a -119 • 3 -126.2 -128.4 -132.2 -148!6 6-8-23b -152.4 -152.8 6-8- 32a -130.0 -131.5 -137.0 6-8- 32b -98.8 -112.4 -110.0 -118. '2 6-8-36 -133.2 -135.8 -135.0 -151.0 7-7-1 Flowing -114.6 -118.6 7-7-3 •■ -82.4 -114.6 -131.0 < concluded on next page) 14 TABLE 7 (concluded) ELEVATIONS OF STATIC WATER SURFACE OF WELLS MEASURED BY COACHELLA VALLEY COUNTY WATER DISTRICT Elevation of water surface (above or below sea level V Well Jan. Feb. Jan. Jan. Jan. Jan. Jan. Jan. REMARKS 1920 1923 1927 1930 1935 1939 1944 1947 1 2 3 4 5 6 7 8 9 10 no. feet feet feet feet feet feet feet 7 r B"-3 -112.5 Flowing -134.7 Flowing 7-8-7d -134.9 -140.9 -141.4 -128 .'8* -156^0 *Probably adjacent deeper well 7-8-17 -127.0 -130.5 -136.2 -141.1 -145.2* -157.0 ♦December 1943 7-8-18 -135.4 -137.2 -147.4 -154.5 7-8-21 -131.8 -134.7 -142.4 -147.8 -155.2* -179.0 ♦December 1943 7-8-34a -135.4 -141.0 -149.6 -154.0 -159.7 7-8- 34d -141.8 -143.4 -151.7 -156.6 -163.4 -166\5 7-8-35c -144.8 -144.4 -154.6 -161.6 Casing cut 200-202, 408-410 7-8- 35d , . -157.8 -161.5 7-8- 35e -151.4 -155.3 -164.5 -173^0 7-9-7 -129.6 -147.7 -160.3 -166.5 7-9-8 -151.6 -158.2 . . Well cleaned in 1939 7-9-20 -156.3* -163.0 -169.0 -183. 3 -186!5 -189 .'8 -203.7 *Feb. 1920 7-9-26 -200.9 -199.0 -203.8 N.G. Surface run-off flows into well (1939) 7-9-30 -182.7 -176.6 -189.3 -I87.O -193.0 -191.2 7-9-33 -192.5 8-8-4b -149.9 -155 .'8 -164.1* ♦December 1943 8-8- lie -136.2 -157.6 -163.7 -171.1 8-8-24b -169.2 -173.5 -182.4 -191.2 8-8-24c -175-5 -183. 9 -191.2 8-9-33f -155.8 -165.9 -177.2 -182.2 -190.2 -195.3 6-8-4A -105.6 -96.9 6-8-16A -129.7 -137.9 -142.4 -148 '.1* Mud ♦November 1943 6-8-18A -109.2 -118.8 -123.4 Dry Location shifted in 1933 6-8- 20A -121.7 -127.I Dry Dry 6-8-21A -141.2 -147.0 -143.0 -157.8 -160 .'7 6-8-25A -161.4 -170.2 -172.6 Dry 6-8- 26A -146.9 -157.0 -159.8 -I65.O* *Nov. 1943 6-8-32A -126.3 -133.8 Dry Dry 6-8-33Aa -139.8 -145.0 Dry 6-8-33Ab -145.0 -155.6 Dry 6-8- 34A -150.1 -156.8 -151.0 -148.7* -151^5 *Nov. 1943 6-8- 36A -166.5 -178.5 Dry Dry 7-8- 2A -182.6 -188.8 -190.6 Dry Dry 7-8-8A -144.9 -156.O -159.4 Dry 7-8-10Aa -169.5* -176/4 Dry Dry Dry ♦Feb. 1927 7-8-10Ab -174.7 -181.3 -185.1 Dry Dry 7-8-11A -187.8 -191.7 -194.3 Dry Dry 7-8-23A -203.1 -204.8 -207.2 -216.1* Mud *Nov. 1943 7-8- 35A -201.4 -202.5 Dry Dry Dry 7-9-l8Aa -199.5 -203.2 -204.8 Caved 7_9_l8Ab -204.7 -208.0 -206.1* -214 .'0 *Dec. 1943 7-9-20A -215.0 -217.4 -219.7 Mud Dry 7-9-22A -219.6 -224.2 -217.2 -223.8* *Nov. 1943 7-9-27A -233.6 -234.2 -234.8 -236.0* Dry' *Nov. 1943 7-9-33A -237.6 -239.2 . t 7-9-36A -234.3 -234.5 -235.5 -236.6* -236.5 *Nov. 1943 8-8-13A -211.2 -216.3 -217.4 -221.8* -213.6 *Nov. 1943 8-9-7A -218.5 -218.8 -219.2 -222.4* Mud *Nov. 1943 8-9-20A -219.7 -209.4 Dry -221.8* -220.3 *Nov. 1943 15 Irrigation canals in Coachella Valley, (credit: U. S. Bureau of Reclamation) 16 TABLE 8 CHEMICAL COMPOSITION OF WELL WATERS USED ON THE FLOODING PLOTS AND OF COLORADO RIVER WATER USED IN LABORATORY EXPERIMENTS. Tract Water Source Electrical Conductivity at 25° C Ca Mg Na co 3 HC0,_, 3 so 4 CI NO Na t no . 1. 2. 3. Well Well Well micromhos/cm 245 246 253 m.e ./l 0.30 0.75 0.25 m.e ./l Trace 0.10 Trace m.e ./l 1.92 1.62 2.00 m . e . /l Trace 0.04 1.35 m.e ./l 1.39 1.51 0.15 m.e ./l 0.53 0.66 0.58 m.e ./l 0.34 0.31 0.36 m.e ./l 0.0 0.06 0.0 per cent 87 66 89 4. Well * 242 254 O.63 0.35 0.11 0.03 1.61 2.05 Trace 0.25 1.58 1.29 0.47 0.52 0.28 0.39 0.04 0.03 69 84 5. 6. Well Colorado Rivert 254 980 0.25 4.78 Trace 1.74 2.17 3-57 1.47 (2 0.05 46) 0.61 5-73 0.34 2.05 0.0 0.08 90 34 * Analyses are not of water used, but of two nearby wells of similar depth. t Analysis of sample collected from East Side Canal in Imperial Valley in February, 1939' t Sodium as of total cations. SALT REMOVAL FROM VALLEY SOILS Leaching Plans for the expansion of agriculture in Coachella Valley through the use of imported Colorado River water contemplate the utiliza- tion of a large portion of the fine textured soils in the trough of the Valley. As previous- ly mentioned, these soils are commonly saline. To reclaim this area will require the leaching of large amounts of salts from the soil profile, and the maintenance of the water table at a safe depth. At present the ground water table is us- ually in excess of 10 feet below ground surface. The decrease in artesian pressure, resulting from increased pumping, has tended to lower the water table in most parts of the Valley. The use of imported water will probably reverse this condition. The bringing of Colorado River water to this Valley will permit use of methods of leaching and flushing which are not now practical with pump flows; and provide a high calcium ratio water on the soils which have become dispersed. Whether it is economically feasible to make the heavy saline soils productive is beyond the purview of this study, but any plan which does not recognize the need for good drainage and the maintenance of a ground water table well below the rooting depth is unsound . We have attempted, however, to secure some field and laboratory data on rate of water percolation into soils of medium to fine texture, and to measure the amount of leaching resulting there- from. Five separate tracts were selected for this study. The waters used were of low salt content, but of high sodium percentage. Table 8 contains data on the well waters used, to- gether with an analysis of the Colorado River water used in the laboratory tests. Experiments on leaching saline soil Tract 1. (Camelthorn) Location: SE^ of NE£ of SW^, section 12, T.7S., R.8E. (See Figure 1.) Soil classification: Indio very fine sandy loam. Depth of water table below ground sur- face: 14 to 18 feet. Land had been farmed at one time . Several experiments were conducted at this location, as follows: a. A plot 10 ft. x 25 ft. was flood- ed 9 times between March 3 and 20, 1937; amounts of water applied were not measured but water passed down to the water table at 14 feet, Comparison of the electrical con- ductance of aqueous extracts from soil samples taken before and aft- er flooding is shown in Table 9. TABLE 9. TRACT No. 1 (a), MARCH, 1937. ELECTRICAL CONDUCTIVITY OF 1-5 AQUEOUS EXTRACTS OF COMPOSITED SOILS SAMPLES TAKEN BEFORE AND AFTER FLOODING. Depth Electrical Conductivity (at 25°C Before flooding After- flooding feet millimhos/cm* ,millImhos/cm* 0-1 1-2 2-3 3-4 8.87 1.70 0.59 0.91 1.51 0.55 0.80 1.39 4-5 5-6 6-7 7-8 0.75 0.28 0.59 1.06 0.89 0.24 0.32 0.49 8 9 9 10 10-11 11-12 0.60 0.68 0.57 0.50 0.54 0.44 0.37 *Millimhos/cm. at 25°C is new electrical conduc- tivity standard for soil extracts . To convert to K x 10- 3 , multiply by 100; to convert to mi- cromhos/cm. multiply by 1000. 17 TABLE 10. CHEMICAL COMPOSITION OF 1-5 AQUEOUS EXTRACTS*0F SOIL SAMPLES PROM A DATE GARDEN AND FROM AN ADJACENT NON-FARMED AREA, TRACT 1(b) June 15, 1938. t Depth Location t PH Ca Na CO3 HCO3 SO4 CI feet p. p.m. p. p.m. p. p.m. p. p.m. p. p.m. p. p.m. 0-1 1 2 9.0 9-0 1100 2350 3622 11982 Tr. 144 397 6100 14086 3018 IO827 1-2 1 2 9.9 9.0 20 690 1202 3207 120 60 198 320 990 7228 H63 2254 2-3 1 2 10.1 10.1 10 50 1035 782 360 300 31 198 1087 838 710 373 3-4 1 2 10.0 10.1 10 30 920 1280 180 360 183 76 898 1704 763 231 * By weight: 1 part dry soil to 5 parts water. t Data provided by D. E. Bliss and Bert Laurence, Citrus Experiment Station, Riverside. t (l) Irrigated date garden, (2) adjacent unfarmed area. b. On June 15, 1938, soil samples were tak- en from an irrigated area in a young date plant- ing just west of plot (a) and in an adjacent area of virgin soil. The water soluble salt content of the soil from the two locations is shown in Table 10 . c. In the period Dec. 9, 1938, to March 1, 1939, a total of 6.3 feet depth of water was applied in 19 irrigations to a plot 20 x 20 ft. square adjacent to the plot described un- der (a) • To minimize any border effect, an area surrounding the plot was flooded at each irri- gation. At the conclusion of the treatment the soil was moist at all depths and the water table stood about 16 feet from the surface. Infiltration rates are shown in Figure 4, (page 27 ) . Comparison of the average salt content of the soil in this plot before and after treat- ment is shown in Table 11. The data indicate that the major portion of the soluble salts was near the surface of the soil and that flooding with local water, a low- salt high-sodium percentage water, caused a marked movement of salt through the soil pro- file. As will be shown later, Colorado River water, a high calcium content water, is a far more effective leachant than the well water used. Tract 2. (Avenue 62) Location: Approximately 50 ft. south of old reservoir in NW^- of NW£, section 2, T 7 S, R 8 E. Soil classification: Indio clay loam. Plot size: 20 ft. x 20 ft. No evidence of water table found in samp- ling to 16 ft. depth. Land had at one time been farmed. TABLE 11. TRACT lc. DEC. 9, 1938 to MAR. 1, 1939 CHEMICAL COMPOSITION OF 1-5 AQUEO0S EXTRACTS FROM COMPOSITED TAKEN BEFORE (B) AND AFTER (A) FLOODING SOIL SAMPLES Depth Electrical Conductivity at 25°C Ca Mg Na CO, + HC0, SO4 CI NO 3 B | A B A B A B A B A B A B A B A feet 0-1 1-2 2-3 3-4 mllllmhos/cm m.e ./l m.e •A m.e /I m.e •A m.e. /l m.e . /l m.e • A 10.79 1.64 1.15 O.96 2.90 O.69 0.55 0.95 27.15 0.60 0.3* 0.3* 0.3 o!2 0.1 1.13 0.1* 0.3* Tr. 0.3 1.2 0.5 0.6 91.3 14.88 10.17 9.08 5.6 5.8 5-3 4.2 1.00 2.18 1.70 4.69 1.3 2.1 3.3 4.4 68.1 7.03 6.46 2.82 0.9 2.8 3-6 3.3 50.0 5.98 2.50 1.58 1.1 0.6 0.3 1.3 1.64 0.13 0.04 0.04 4-5 5-6 6-7 7-8 0.44 0.35 0.64 0.64 0.56 0.42 0.55 0.71 0.2* 0.2* 0.85 0.4* 0.1 0.1 0.1 0.1 Tr. 0.2* 0.23 Tr. 0.1 0.1 0.1 0.1 3.93 2.82 4.76 5.67 5.0 3.8 4.6 6.2 1.63 1.21 0.87 2.34 2.2 1.4 1.2 2.2 1.75 I.65 3.94 2.36 2.1 1.4 2.3 2.5 0.77 0.65 1.15 1.38 1.1 0.7 1.2 1.6 Tr. Tr. 0.02 0.02 8-9 9-10 10-11 11-12 0.63 0.82 0.65 0.48 0.53 0.52 0.41 0:38 0.44 0.63 0,59 0.4L 0.1 0.1 0.2 0.2 0.2* 0.58 Tr . 0.1 0.1 0.1 0.1 0.1 5.14 6.44 4.81 3.44 4.4 4.5 3.5 3.0 1.76 1.21 0.87 0.97 2.1 2.0 1.6 1.5 2.58 4.46 3.38 1.94 1.5 1.6 1.3 l.l 1.37 1.90 1.45 1.02 1.0 1.0 1.0 0.7 0.01 Tr. 0.02 0.00 12-13 13-14 14-15 15-16 0.53 0.50 0.80 0.40 0.26 0.29 0.20 0.21 0.57 1.05 2.59 1.00 0.2 0.1 0.2 0.4 0.1 Tr. 0.1 Tr. 0.1 0.1 0.1 0.1 3.74 3.32 5.03 2.57 2.0 2.4 1.6 1.4 1.01 0.75 0.63 0.67 1.4 1.6 1.3 0.9 2.41 2.74 4.94 I.96 0.5 0.7 0.4 0.8 1.02 1.00 2.02 0.85 0.4 0.4 0.2 0.2 0.00 Tr. 0.06 0.02 * Seml-quantltatlve estimations by direct comparison with known amounts of the precipitate. 18 o • -H fl -P CO cd • R •H •• -P -P Cd tH bCO •H 19 TABLE 12. TRACT No. 2, DECEMBER 9, 1938 - MARCH 4, 1939 CHEMICAL COMPOSITION OF 1-5 AQUEOUS EXTRACTS FROM COMPOSITED SOIL SAMPLES TAKEN BEFORE (B) AND AFTER (A) FLOODING (Wet to a depth of about 5 feet) Depth Electrical Conductivity at 25 C Ca Mg Na CO + HCO SO4 Cl N0 3 B A B A B A B A B A B A B A B A feet 0-1 1-2 2-3 3-4 4-5 I- 6 6-7 7-8 8-9 9-10 10-11 11-12 12-13 13-14 14-15 15-16 mllllmhos/cm m.e./l m.e./l m.e./l m.e./l m.e./l m.e ./l m.e./l O.56 0.53 0.47 1.23 0.44 0.45 6'. 3,1 0.19 0.18 0.20 0.22 0.14 0.09 0.08 0.08 0.22 0.17 0.24 0.41 0.57 1.07 0.80 0.51 0.22 0.17 0.15 0.12 0.1* 0.12 0.12 1.05 1.0 0.4* 0.1* 0.1* 0.1* 0.1* 0.15* 0.25* 0.35* 0.1 0.1 0.1 0.2 0.1 1.4 1.1 1.1 0.4 0.09 Tr. 0.05 0.1* 0.13 0.0* 0.23 0.2* 0.2 0.2* 0.2* 0.3* 0.2* 0.2* 0.1* 0.2* 0.3 0.2 0.1 0.2 0.8 0.6 0.3 0.3 0.1 5.04 4.98 4.30 11.32 3.88 3.89 3.47 I.87. 1.01 1.41 1-59 1.67 1.11 0.62 O.96 0.42 2.0 1.8 2.6 4.2 5.1 8.8 5-9 3.2 1.6 1.54 1.86 1.41 2.88 1.17 0.93 0.77 1.12 0.67 0.63 0.64 0.72 0.75 0.65 1.17 0.66 2.2 1.4 1.8 2.6 1.2 0.8 1.0 0.9 0.8 3.17. 2.57 2.16 5.47 1.91 2.24 2.25 0.4* 0.4* 0.35* 0.45* 1.2* 0.4* 0.1* Tr. Tr. 0.3 0.2 0'.2 0.3 2.8 5.4 3.8 2.3 0.8 0.90 0.65 0.80 2.75 0.75 0.95 1.75 1.82 0.41 0.40 0.40 0.35 0.20 0.19 0.15 0.24 0.1 0.1 0.1 0.8 2-9 1.9 1.3 0.4 0.07 0.05 0.03 0.05 0.04 0.02 0.02 Tr . 0.04 0.02 0.03 0.02 0.01 Tr. * Semi-quantitative estimates by direct comparison with amounts of the precipitates. In the period December 9, 1938, to March 4, 1939, a total of 6.7 feet depth of water was applied in 19 irrigations to the plot. To mini- mize border effect, an area surrounding the plot was flooded at each irrigation. At the conclusion of the experiment the soil under the plot was moist to a depth of only 5-5 to 6.5 feet. Apparently the soil at this depth was relatively impervious and the water applied mov- ed off laterally thruugh a more permeable stra- tum. Infiltration rates are shown in Figure 4. Comparison of the average salt content of the soil in this plot before and after treatment is shown in Table 12. This soil was not as saline at the start of the test as that of Tract 1. Applications of well water caused a leaching of the salt from near the surface. A slight increase in salt content occurred, in the stratum immediately be- low the porous layer through which water moved laterally. Tract 3: Location: Near North side of SW^ of NW-J of NE£, Section 17, T 7 S, R 9 E. Soil Classification: Indio very fine sandy loam. Depth of water table below ground sur- face: 13 feet before leaching, 10 to 13 feet after leaching. Land had been farmed a few years prior to test. In the period December 28, 1938, to March 2, 1939, a total of 9.4 feet depth of water was applied in 17 irrigations to a plot 20 x 20 feet square. As in the case of the other plots, an area surrounding the plot was flooded at each irrigation. Infiltration rates were high- er for this plot than for the two other plots operated at the same time. Changes in the salt content of water extracts of soil samples taken before and after leaching treatment are shown in Table 13 . Leaching of salts from the highly saline sur- face soil into the ground water was readily ac- complished in this trial. At the end of the test, the ground water, which stood at about 10 feet, was highly saline. Tract 4: Location: At SW corner of NW-5- of NE£, Section 4, T 7 S, R 8 E. Soil Classification: sandy loam. Indio very fine Composite samples were obtained from two adjacent locations. Plot 1 (irrigated land) had at one time been planted to alfalfa which at first did well, but after a few years the soil was re- ported to have "tightened-up" and a local high water table developed. Since then the artes- ian discharge of the wells had been allowed to flow over the land continuously to provide pas- ture. A dense growth of mesquite covered the area. The location where the soil samples were obtained had been flooded almost contin- uously for years . Plot 2 ("virgin soil") Is in the NW£ of Section 4, located within 50 feet of plot 1; it had never been cropped. Except for the differences arising from treatment, the soils are similar. Table 14 represents, then, salt content differences resulting from a long con- tinued flooding with water from an artesian well . The data indicate that the non-flooded soil through a depth of 10 feet was far more saline than the plot that had been flooded. Below 10 feet, where the soil is saturated, the salt conditions were similar in both plots. Tract 5: Location: S| of NW£, Section 29, T 7 S, R 9 E. Soil classification: Woodrow loam. This location is within the area flooded by Salton Sea in 1907. The soil is fine textured and has a high salt content. Table 15 gives an analysis of the salt content of water extract of soil samp- les collected in increments of 1/10 foot to a depth of one foot, together with an analysis of the salt crust which was approximately one- eighth inch thickness. 20 TABLE 13- TRACT NO. 3, DEC. 28, 1938 - MARCH 2, 1939 1 CHEMICAL COMPOSITION OF 1-5 AQUEOUS EXTRACTS FROM COMPOSITED SOIL SAMPLES TAKEN BEFORE (B) AND AFTER (A) FLOODING. Electrical Depth Conductivity Ca Mg Na CO + HCO SO;, CI N0 S at 25 "c B A B A B A B A B A B A B A B A feet 0-1 mllllmh 03/cm m . e . /I m.e A m.e ./l m.e A m.e . A m.e A m.e ./l 9.18 0.29 13.14 1.1 1.84 0.2 80.13 1.3 0.83 1.0 45.20 0.1 49.25 0.2 0.29 1-2 2.52 0.20 1.82 0.1 0.82 0.1 20.90 1.7 0.89 1.2 13.74 9-38 0.1 0.07 2-3 4.20 0.34 13.13 2.2 3.19 0.2 29.10 1.0 0.85 1.0 32.10 1.4 13.10 0.1 0.05 3-4 1.85 0.18 0.60 0.2 0.25* 0.1 16.04 1.6 1.17 1.1 7.67 0.6 8.45 0.1 0.06 4-5 1.31 0.28 0.15 0.1 Tr. 0.2 12.17 2.8 0.84 2.5 4.62 0.4 5.68 0.1 0.13 5-6 1.48 0.41 0.12 0.2 0.17 0.2 13.75 4.1 1.94 4.5 5-33 0.4 6.55 0.1 0.08 6-7 2.67 0.59 0.1» 0.2 0.2* 0.4 24.15 6.0 1.82 5.7 9.72 1.3 12.98 0.2 0.09 7-8 2.76 1.23 0.1* 0.2 0.1* 0.5 24.59 11.5 1.62 3.4 9.44 4.5 14.15 3.7 0.07 8-9 3.21 1.68 0.39 0.3 0.1* 0.5 29.78 2.9 1.84 2.9 11.15 6.4 16.70 5.8 0.16 9-10 3.36 2.26 0.1* 0.1 0.1* 0.3 32.01 20.9 1.51 1.6 11.34 8.0 18.95 9.9 0.19 10-11 3.32 3.12 0.2* 0.2 0.1* 0.2 30.84 29.0 1.49 1.4 11.35 10.7 18.00 15.4 0.06 11-12 3.36 2.80 0.4* 0.3 0.1* 0.4 30.75 26.4 1.68 1.4 11.51 8.8 18.05 14.0 0.11 12-13 2.74 2.83 0.37 0.3 0.1 0.3 25.08 26.8 1.11 1.5 9-85 8.3 14.50 14.5 0.1 13-14 2.71 2.96 0.29 0.3 0.1 0.3 24.69 27.9 1.21 1.4 9.81 8.9 14.28 15.1 0.06 14-15 2.60 2.98 0.26 0.3 Tr 0.4 23.93 27.8 1.15 1.3 9.80 8.8 13.48 15.4 0.06 15-16 2.51 2.77 0.30 0.3 Tr 0.4 22.34 25.7 I.09 1.5 8.80 8.1 13.20 14.3 0.06 Semi -quantitative. On Tract 5 are located ten large ponds, each with a gross area of 5 acres, which are flooded at least 5 months each year to provide duck hunting In the fall. Measurements were made of the average rate of drop of the water- In these ponds after inflow was stopped for the year. Average values are shown in Table 16. After the ponds had dried, soil samples were obtained from k ponds on the north side. Simi- lar soil samples were obtained along an east- west line 40 feet north of the ponds. The lat- ter samples represent unirrigated soil, but the entire area has been briefly inundated from time to time during heavy floods. A comparison of the salt content of the soil from the two locations described above is shown in Table 17. The results of leaching are shown graphical- ly In Figure 5, (page 28). Although experi- ments on the various plots indicate that, in most instances, the soil can be leached of ex- cessive salts, the infiltration rate data ob- tained (Figure k and Table 16) are such as to raise doubts as to the practicability of main- taining, in all cases, reasonably low soil- water salt concentrations under the irrigation practices that could be expected to follow leaching, and with the present irrigation wat- ers. This is in line with the general exper- ience of farmers on these saline soils. Many enterprises have been abandoned, and those con- tinuing do not appear too profitable. In explanation of the infiltration data of Figure k, it might be said that in general in- filtration rates decrease with time. Rates are highest when water is first applied, the rates decreasing rapidly at first, and then more and more slowly until they become almost uniform. TABLE 14 TRACT 4 CHEMICAL COMPOSITION OF 1-5 AQUEOUS EXTRACTS TAKEN ADJACENT TO FLOODED PLOTS (B) AND FROM COMPOSITED SOIL IN FLOODED PLOTS (A) SAMPLES Depth Electrical Conductivity at 25 C C a Mg Na CO3 + HCO3 S04 CI NO, B A B A B A B A B A B A B A B A feet mllllmhos/cm m.e ■ A m.e ■A m . e . /l m . e . /I m . e . /I m.e A m.e A 0-1 1-2 2-3 3-4 15.22 9.33 5-03 2.97 0.41 0.20 0.15 0.17 56.2 6.1 1.4 0.8 2.1 0.6 0.7 0.5 6.9 1.2 0.3 0.3 0.5 0.1 0.2 0.4 IO5.6 74.0 38.1 22.1 1.0 0.9 0.3 0.3 1.7 1.2 1.1 1.2 2.3 1.6 1.3 1.4 109.6 28.2 11.8 6.7 1.2 0.3 0.2 0.2 25.8 14.4 0.4 0.0 0.1 4-5 5-6 6-7 7-8 0.88 0.77 0.90 1.30 0.09 0.08 0.12 0.15 0.2 0.1 0.3 0.6 0.4 0.3 0.5 0.5 0.1 0.2 0.1 0.2 0.4 0.1 0.3 0.4 5-0 5.3 7.1 9-7 0.2 0.2 0.2 0.3 1.1 1.3 1.2 0.9 0.9 1.0 1.3 1.6 2.2 1.6 2.2 4.4 0.1 0.1 0.1 0.1 2.6 3.0 3.1 4.5 0.1 8-9 9-10 10-11 11-12 1.84 2.40 0.71 0.54 0.23 0.43 0.53 0.56 0.6 0.3 0.1 0.1 0.5 0.1 0.2 0.1 0.2 0.2 0.1 0.1 14.4 19.3 5.4 4.4 2.9 1.8 3.9 3.7 1.3 2.1 2.7 2.3 1.6 2.8 3-3 3.7 6.3 6.7 0.7 0.6 0.1 0.1 0.4 0.4 5.6 9.1 1.7 1.4 0.1 0.2 0.1 0.1 12-13 13-14 14-15 15-16 0.53 0.55 0.57 0.55 0.53 0.49 0.50 0.54 0.2 0.4 0.3 0.3 0.2 0.1 0.1 0.2 0.2 0.1 0.2 0.2 4.2 6.0 4.2 4.2 3.4 3-5 3.7 3.0 2.3 1.8 2.2 2.0 3.0 3.0 3-1 3.1 1.0 2.2 1.3 0.9 0.6 0.5 0.6 0.6 1-3 3.0 1.4 1.3 0.2 0.2 0.2 0.2 21 TABLE 15 DISTRIBUTION OF SALT IN A SURFACE FOOT OF WOODROW SILTY CLAY LOAM SOIL IN INCREMENTS OF 1/10 FOOT, 1-5 AQUEOUS EXTRACT. Electrical Conductivity at 25°C Ca Mg Na K HCO^ so 4 CI NO, Depth feet millimhos/cm m . e . /l m . e . /l m . e . /l m.e ./l m.e ./l m.e ./l m.e./l m.e./l Salt crust* .0- .1 28.9 42.1 1.0 313 2.1 1.8 202 157 0.4 .1- .2 27.3 26.6 1.4 305 1.5 1.0 154 180 0.2 .2- .3 23.4 21.1 1.3 245 1.4 1.0 82.1 182 0.2 .3- A 23.4 27-5 1.4 230 2.0 1.0 89.2 170 0.2 .4- .5 27.3 29.4 2.3 274 2.7 0.9 99-6 211 0.3 .5- .6 27.3 11.9 2.3 277 2.3 0.9 82.7 211 0.2 .6- .7 19.6 4.5 1.7 201 1.6 1.1 53-9 153 0.2 .7- .8 15-3 3.2 1.5 155 1.4 1.1 42.8 118 0.2 .8- .9 17.2 4.6 1.3 177 1.4 1.8 50.6 134 1.1 .9-1.0 16.4 3-8 1.8 169 1.2 1.2 46.7 124 0.2 * A salt crust of approximately 1/8" thickness covered the ground. The percentage composition of this salt was as follows: Ca. 0.15, Mg. SO4 5.38, CI, Tr., Na 54.6, NO 38.2, K. 3 0.31. 0.10, CO3 0.34, TABLE 16 AVERAGE RATE OF DROP (INFILTRATION PLUS EVAPORATION) IN INCHES PER DAY FOR PONDS Al, A2, A3, A4, Bl, B2, B3, B4, AT TRACT 5. Interval Rate From To Date 11-25-38 Hour 3:25 p Date 11-29-38 Hour 10:20 a Inches per day 0.142 11-29-38 10:20 a 12- 1-38 7:25 a 0.109 12- 1-38 7:25 a 12- 3-38 10:30 a 0.192 12- 3-38 10:30 a 12- 5-38 10:30 a 0.138 12- 5-38 10:30 a 12- 7-38 10:30 a 0.144 12- 7-38 10:30 a 12- 9-38 10:30 a 0.150 12- 9-38 10:30 a Rain - in1 12-11-38 :ermittent 12:00 n 0.109 12-1938 11:00 Ra: 12-21-38 .n 2:30 p 0.074 12-23-38 12:00 n 12-28-38 11:00 a 0.167 12-28-38 11:00 a 12-30-38 11:45 a 0.095 12-30-38 11:45 a 1- 1-39 12:00 n 0.107 1- 1-39 12:00 n 1- 6-39 11:00 a 0.056 1- 6-39 11:00 p 1-12-39 4:00 p 0.031 1-12-39 4:00 p 1-19-39 12:00 n 0.114 22 TABLE 17 TRACT NO. 5, 1938 CHEMICAL COMPOSITION OF 1-5 AQUEOUS EXTRACT PROM COMPOSITED SOIL SAMPLES TAKEN ADJACENT TO (B) AND IN FLOODED PLOTS (A) Depth Electrical Conductivity at 25°C Ca Mg Na CO, + HCOo SO 4 CI NO3 B A B A B A B A B A B A B A B A feet 0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 mlllln 9.27 5-99 4.35 4.50 I.85 1.41 1.46 1.27 1.11 ihos/cm 11.33 3.61 1-51 1.55 1.32 0.54 0.59 0.78 0.53 m.e 3.47 0.32 0.05 0.10 0.02 0.27 0.20 0.45 0.17 A 3.5 0.4 0.2 0.2 0.1 0.1 0.1 0.1 0.1 m.e 0.52 0.10 0.37 0.11 0.27 0.15 0.20 0.45 A 1.1 0.5 0.2 0.1 0.2 0.3 0.2 0.1 0.1 m . e . /l 89.6 107.4 56.9 27.8 41.5 H.6 40.2 11.0 15.50 9.6 11.53 4.5 12.86 5.9 10.94 7.3 9 - 37 5.3 m.e 1.13 2.34 1.49 1.49 1.09 O.69 3.H 3.15 0.81 A. 1.8 2.3 1.7 0.1 1.5 1.3 4.5 4.0 3.8 m . e . /I 29.64 40.0 15.57 6.2 11.44 2.6 9.28 4.7 4.09 4.2 3.37 1-5 3.20 0.2 2.23 0.2 3 . 05 0.1 m.e 62.5 39-4 28.4 29.6 10.20 7.95 7.15 6.08 5.90 A 68.4 20.9 7.7 6.5 5.2 1.7 1.3 2.5 1.6 m.e/l 0.31 0.1 0.15 0.13 0.15 0.11 0.05 0.05 0.06 0.06 Infiltration rates on the plots were establish- ed by periodic hook gage readings of the water surface, with computations being made to estab- lish the average rate in each interval between readings. In Figure 4, the medium weight ver- tical lines represent the time readings were made, and the heavy horizontal lines represent average rates for the intervening periods. The last reading of any irrigation and the first reading following the next irrigation are con- nected by light lines. There was frequently some recovery in rate with each irrigation, de- pending largely upon the time the plots dried out between irrigations, but such recovery did not' approach the initial rates of the first ir- rigation of each plot. Some data have been obtained on the macro- pore size distribution of surface soil from Tract lb and Tract 5 (unirrigated soil). These data, summarized in Table 18, do not show any inherent physical characteristic that might preclude satisfactory agricultural usage if the soil were drained and irrigated with a wat- er of lower sodium percentage. TABLE 18 MACR0P0R0SITY FOR SURFACE FOOT OF SOILS OF TRACTS lb AND 5. Laboratory studies of leaching Approximately 800 grams of air-dry soil from the surface half- inch of Tract 1 were placed in each of six split case tubes 15 inches long and about 2 1/8" in diameter. The bottoms of the tubes were cone-shaped and perforated. The soil filled the tubes to within about 3 inches of the top. Two sets of 3 tubes each were equipped with constant water level devices. To one set water from well 1, of Table 5> a high sodium water was applied; to the other, Colorado River water. During the first few days the amount of water percolating through the soil column was approximately the same for both sets, but at the end of two months the ratio was approxi- mately 2z to 1 in favor of the Colorado River water. The percolation rates at the end of the run were in all cases much lower than the ini- tial rates. Base exchange studies made after the runs were completed showed an average sodium per- centage of 56 for the soils receiving high sodium water, and 36 per cent for those receiv- ing the Colorado River water. Under field conditions, with alternate wet- ting and drying of the soil combined with the effect of plants growing on the soil, we would expect that the percolation ratio would, in time, be much more favorable to Colorado River water than is indicated by these tests. Location Tract lb* Tract lbt Tract 5J Macropor- osity § per cent 12.9 8.7 16.6 Apparent specific gravity 1.23 1.19 1.07 ♦Manured and flood-irrigated area in date planting . tNon-f ertilized adjacent irrigation ditch. tUnirrigated area. §Macroporosity assumed to equal volume of pores drained when the tension of the soil water is increased from to 40 cm. of water. Flushing Data in Tables 9 to 17 indicate that a re- latively high percentage of salines are found on or near the soil surface. The feasibility of salt removal from the soil surface by flushing was investigated and found to have promise. Although this method is more limited in its application than the leaching method it does permit the direct removal of salines with- out having them pass through the soil profile. In July, 1938, samples of spill water from the end of a basin- irrigated date orchard near Tract 1 (b) were collected at half hour inter- vals. The electrical conductivity measurements of these samples are reported below. The re- sults are only qualitative since run- off was not measured. The conductivity of the irriga- tion water as it entered the orchard was about 250 mlcromhos/cm. 23 Hours after run- off started hours i 2 1 Electrical Conductivity at 25°C of surface drainage 1st Irrigation 2nd Irrigation Micromhos/cm Micromhos/cm 6160 5070 5660 3990 10590 8260 7980 7610 In April, 1939, an area was selected adjac- ent to the unirrigated area of Tract 5, and strip checks of approximately one- hundredth of an acre were developed. The Spring winds, which are common to the -Valley, had blovn away some of the salt crust that had been especially noticeable earlier in the year. Soil for the levees was borrowed from out- side the check so as not to remove the salt crust from the soil within the check. Water- measuring flumes were installed at the entrance and exit of the checks, and water samples were collected at intervals throughout the run. Electrical conductivity determinations were made on water samples, and in a number of cases total solids were determined. The first efflu- ent was very saline, as Indicated in Figure 6, (page 29) . The first run was made on April 6, 1939- On April 27, another test was run. Prior to the second run, the soil surface was white with salts, mainly sodium chloride. The first water to pass from the check was extreme- ly saline, its salt content being in excess of 40,000 p. p.m. The salt concentration dropped very rapidly as water passed over the soil. These data indicate that with the wastage of relatively small amounts of water large amounts of salt can be removed directly from the sur- face of the soil. This offers a method of salt removal, especially during the early stage of reclamation. It is not a complete method of salt removals, however. Attention should be called to the fact that flushing accomplished more, in each case, in the second irrigation than in the first. Some upward capillary move- ment of salt in the top inch or two during the intervening period appears to be indicated. Reclamation and Drainage The conclusion of these investigations is that most of the highly saline soils of the Coachella and Indio series, other than the very fine Indio clays, can be reclaimed and contin- uously utilized provided that they are properly irrigated with Colorado River water, and fur- ther, provided that the soils are adequately drained. The profitable use of the soils of the Woodrow series for general crops is ques- tionable. Reclamation methods might include both flushing and leaching. The chief problems associated with the in- crease in irrigated area will concern the pre- vention of a general high water table and, more locally, overcoming difficulties attributable to perched water tables above abrupt changes in soil texture. In regard to the prevention of a general high water table, emphasis must be plac- ed on the maintenance of pumping. Additional pumping from wells located above the area to be served with imported gravity water would cause lowering of piezometric levels below, and so help to relieve the drainage problems of the lower trough. Percolation from gravity- irrigated areas should be of considerable magnitude, and should necessitate extensive drainage measures in or- der to utilize the lands of the lower trough, both those which are now saline and those which are under cultivation. Thus there are two phases of the drainage problem: a. Maintenance of the normal ground waters at reasonably low levels by pumping for irri- gation. b. Removal of relatively shallow perched waters originating in the irrigation of up- stream or overlying lands. Much of the latter water will undoubtedly be too saline for further utilization. Considerable stratification, with abrupt textural changes, is the rule with Coachella Valley soils. This condition adversely affects the permeability of the profile, and many perched water tables have been observed (11) above such changes in texture. Such perched water tables, although essentially temporary in nature, will affect drainage when close to the surface. Throughout most of the Valley the strata closely parallel the ground surface , and are rather discontinuous as evidenced by soil sampling to 18 food depth and by comparison of- well logs to considerable depth. The least per- meable and most continuous strata are found near Salton Sea. Such layers, when close to the sur- face, may impede reclamation. 24 Fig. 1. Map of a portion of Coachella Valley, California, showing ground water contours as of January, 1939, the 1936-37 irrigated areas, wells measured for static water level, and wells for which chemical analyses of the water were made (together with key numbers indicating the type of water) . Moqnesium (me./ I.) 1 I 4-4-23 I i 4-4-25 i 4 - 5 ' 33 i 4-5-13 i 5-5-13 1 i 5-61 1 i 4-628 1 i 5-6-2lc | i 5-6-2IQ i 4-6-27 || b-6-22j 1 i 5-622 d i 5-6-22c 5-7-6 i 5-7-30o i 5-7-22o | i 5-7-21* | i 5-7-2lb i 5-7-28c 5- 7-28 b i 5- 7-28 o i 6-7-4 a i 6-6- 1 r i 6-7-4 b 5- 7-34b i 5- 7-24 i 5-7-JS | i 5-7-2S i 6- 7 -23 b i 6- 7-23o i 6-7- lb 1 i 6-7- la 1 i 6- 7 -13 a i 6- 8 - 6 a i 5-8-31° | I 5-8-3lb i 6-717 | d 6-7-24 1 i 6- 8- 6b i 6-7-25 1 i 6-e-s 6-8-17 | 6-8-20 i 6-8-21 i 6-8-10 6-8-32b r i 6-8-1 In 1 6- 8 - 1 1 b | i 7-8-4a I i 7-S-7c | 7-8-7* I 7-8-7b | 7-8-4b 1 6-8-28 7-8-20 | 6-8-36 i 7-8- 2 b I i 7-ft2a | i 7-8-16 i 6-8-25 i 6-8-24 i 7-6-34a 7-8-34b 7-8-12 7- 8 -34c 7-8-35f 7-8-35b i 7-6-35a 1 i 8-8- II o 8-8- II b 8-8-I0 8-8-14 8- 8- lb i 8- 8-l3o i 8-8- 13b ] 7-9-8 1 r~ 7- 9- 17 7-9-16 1 7-9-29 7-9-21 1 7- 9- 22a 7-3-27 Per cent sodium as of Total cations Pig. 2. Chart showing per cent sodium and magnesium content of water for all wells from which samples were obtained for analysis which had a conductance of 50 or less, progressing down the valley (from left to right of Figure l) . 25 1920 1925 1930 1935 1940 1945 Year Fig. 3- Ground water fluctuations for key wells selected on the basis of geographical distri- bution and length of record. 26 Infiltration capacity (plus evaporation) Inches per day - 1 m +■ u o L. ►- 1 1 1 l »! -a c ■a i_ o « u a L L U "•- i J> *~ a O L -Q (0 "O 0"» £ § o) > CL < — 1 i - 1 - i f .J -' L £ 1 ] ■ ■ 1..: 1 1 i j 1 . i r i 1 ,-! I .__ • _| 1 1 I rnqations 1 I. i l _l u ■t- b C u ►— 1 -l • 1 1 vy n 4 ■ - 1 1 J 1 1 4- 8 ■ i 1 J 1 f \ i J — 1 o <0 o 10 <0 27 p **> ct a> '*! M . a> o> ui o . zr H- fa W . 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