The water resources of the Las Vegas Valley: a brief survey, March 27, 1931

THE WATER RESOURCES of the LAS VEGAS VALLEY A brief survey March 1931 PRELIMINARY SKETCH OF THE WATER SUPPLY PROBLEM OF THE LAS VEGAS VALLEY CONTENTS Photostatic Lap of the Las Vegas and Adjacent Valleys page I Introductory 1 Area of Watershed - Las Vegas Valley 1 Table - Drainage Areas - following 1 Watershed Areas in Addition to the Charleston Range 5 Pahrunp Valley 3 Mesquite Valley 4 Indian Springs Valley 4 Indian Springs Valley - sketch and profile map - following 4 Owens Dry Lake 5 Corn Creek 5 Tule Springs 6 West Side of the Las Vegas Valley 6 Rest Side of the Las Vegas Valley - sketch and profile map 6 West Side of the Las Vegas Valley - table of elevations 7 Table of Water Analyses - following 7 Ivanpah Valley 8 Ivanpah Valley - sketch and profile map - following 9 Ivanpah Valley - table of elevations 10 Further Consideration of Factors in the Las Vegas Valley 10 Recapitulation 12 Discussion of the Charleston Park Area 12 PRELIMINARY SKETCH IF THE '-YATE1 SUPPLY PROBLEM OP THE LAS VEGAS VALLEY Introductory The essential factors in a water supply are the size and character of the watershed end the total depth and character of the precipitation. The size of the drainage area and the total depth of the annual precipitation determines the possible runoff, while the character of the area and of the precipitation determines the actual runoff. From these two factors it is possible to calculate and predict the runoff from any given area. To arrive at any correlation between the possible supply and the actual runoff it is necessary that the discharge be in a measurable form. That is, the runoff must show in streams, springs, flowing wells or areas of mea-surable ground water discharge. In the following discussion these factors are considered for the Las Vegas Valley. Watershed: In considering the water supply for the Las Vegas Valley, attention must be given to the extent and character of the drainage area. Since it is quite evident that the rainfall in this interior region varies directly with elevations, it is necessary to know the area of watershed at the various elevations. When this is known it is then necessary 'to determine the rainfall for each individual elevation, and since the storms in this area are very apt to te quite local in extent it appears that many stations at each elevation would be required to secure a true average. Snow measurements would be necessary on the higher elevations. Area of watershed The watershed for the Las Vegas Valley is quite large, especially when the drainage areas of the adjacent con- tricuting valleys are considered. On the accompanying large map are shown the relationship of the various valleys and their drainage areas to the Vegas Valley, and an approximation of the areas for each WATERSHED DRAINAGE AREAS . C.ont ou?. Area 1 - Las Vegas Valley t 4 5 6 7 , R ' 9 10 11 Total Sheep Range 76.75 63.0^ 73 ..05 31.30 ! 31.20 4.30 0.00 00.00 279.65 CKHrleston Ranae 4-132.JKL nn.Qh FSA, T.o f.n lo, Kn ' r, yn 3.35 352.35 Total 208.95 144.00 127.70 67.70 50.80 23.90 5.70 3.35 632.00 Arua* is* ^ uwens Dry EaRe 36.60 11.65 1.45 0.00 0.00 0.00 0.00 0.00 50.70 Area 15 - -*or;;;on ^ulcn 164.35 92.10 9.85 2.35 0.00 0.00 0.00 0.00 268.6o Yotai Area i 410.90 247.75 139.00 70.05 50.80 23.90 5.70 3.35 940.90 Area 2 - Ivanpah Dry Lake 248.90 147.30 16.80 2.40 0.80 0.00 0.00 0.00 416.20 ^rea 2D - Jean i/ry laKe . 5.20 .50 0.00 0.00 0.00 0.00 0.00 29.40 Total .area 2 272.60 152.50 17.30 2.40 0.80 0.00 0.00 0.00 445.60 .urea 3 - Indian Spgs. Valley Spotted Range 156.05 102.55 2.10 0.00 0.00 0.00 0.00 0.00 260.70 unarieston Kange 73.00! 55.45 43.70 28.40 10.15 6.40 1.60 0.00 218.70 ' T6tal Are^ 3 aaa.os 158.00 45.80 28.40 10.15 -6.40 1.60 0.00 479.40 Area 1 plus Area 3 - total 433.00 301.90 173.50 96.10 60.95 30.30 7.30 3.35 1420.30 Area 1 plus Area 2 - total 683.50 400.15 156.30 72.45 51.60 23.90 5.70 3.35 1386.50 Area 1, Area 2, Area 3 - 912.55 558.15 202.10 100.85 61.75 30.30 7.30 3.35 1865.90 Area 4 - Pahruxp Valley Charleston Range 156.70 98.60 94.-60 62.50 29.70 17.30 10.05 3.50 472.95 Area 5 - Lesquite Valley Charleston and other Ranges 113.40 33.8C 8.60 2.60 1.00 0.00 0.00 0.00 159.40 Total all Areas 1182.65 690.55 305.30 165.95 92.45 47.60 17.35 6.85 2508.70 Charleston Park ..atershcd Area 22.00 25.9C 20.90 16.60 9.70 6.90 4.10 1.90 108.00 1000 foot interval from the 3500 foot contour to the tops of the various ranges. These areas are shown on the accompanying table. This map was constructed from the topographic sheets cover-in.. this area. The drainage divides were then established and the various areas determined by cross-sectioning. The method is subject to some criticism on the score of accuracy, but is probably as close an approximation as the present contour maps will permit. It will be noticed that the central mass of the Charleston Mountains is bordered on the west by two closed basins, the Pahrump and Mesquite Valleys. On the extreme north a small area drains into the Ash Meadows and so on into the Death Valley drainage. To the northeast the drainage from Mount Charleston is toward the Indian Springs Valley, while a little farther east a small section contributes to a small dry lake, identified on the map as Owens Dry Lake. These two areas and a slightly higher lying dry lake north of Owens, called the Mormon Gulch, are all believed to have an underground outlet into the Las Vegas Valley. Proof of this assumption has not been fully developed, but it is submitted later on in this paper on the basis of the present data. The next drainage to the south is that of the Las Vegas Valley. All the eastern and southern exposures of tne Charleston Range, with the exception of a small area on the southern end of the Potosi Mountain which drains into hie Ivanpoah Valley, contribute to the Las Vegas Valley. South and west of the Las Vegas Valley lies the Ivanpah Valley. In addition to the drainage from the Goodsprings section of the Potosi Mountain this dry lake receives the drainage from the low mountains that almost completely encircle the valley. The annual increment to the Ivanpah Valley is not great, but whatever amount gets into the sediments underlying the lake must finda an outlet. Incomplete data will be pre- TILBhR and SNOW Views on north slopes of Sawmill Canyon, taKen Larch 20, 1931. The mountain ridges shown arc part of the Spring mountain Range lying immediately north of Lt. Charleston. Two Small Flowing Wells in tho Las Vegas Valley. The Southern Nevada Land and Development Co's well y3. Rew .oil in the Las Vegas City Park. sented indicating the possibility that this outlet is toward the Las Vegas Valley. Watershed areas in addition to the Charleston Range: While the Charleston Range is of greatest impor-tance as a source of water in this section, other mountainous areas must be considered also. On the east and north-east of the Las Vegas Valley are the low Sunrise Mountains and the Las Vegas Range. A little farther to the north rises the considerable bulk of the Sheep mountains. Most of the runoff from the west end of the Sheep Mountains is directly into the Las Vegas Valley, tho a small area drains into the Owens Dry Lake. The east end of this range drains toward the Muddy River. The Owens Dry Lake and the Mormon Gulch Dry Lake are bordered on the north, east and west by rather low ranges. The total area draining into the Mormon Gulch is large, 416 square miles, but practically all of this area lies below the 5500 foot contour. The contributing area of hills to the Indian Springs Valley from the Desert and Spotted Ranges on the north and east is actually greater than that from the Charleston Range. However 258 out of a total of 260 square miles of the Desert and Spotted Ranges lies below the 5500 foot contour, while only 128 out of a total of 219 square miles on the Charleston Range lies below this level. Pahrump Valley Little attention need be paid this valley in the present discussion. It seems to be a completely enclosed basin and all the water entering into the valley either reappears as springs or flowing wells to be lost thru evaporation and transpiration, or finds its way thru underground channels to the low point of the valley, where in Stewart Valley is a large area with a high water table where ground water discharge is taking place. The two means seem to be sufficient to take care of all the increment to the Pahrump Valley. It might be mentioned in passing, however, that there is a possibility that some water may escape northward from Stewart Valley and ap- ^Mowing Approximate Locations / walls on line from Indian Springs to Las Vegas pear in the Ash Meadows. This situation would require a little closer consideration than has been given if any serious attempt were made to correlate the precipitation on the mountain with the runoff in this valley. Aside from the possibility of a leak into the Ash Meadows the Pah-rump Valley probably offers the best set of natural conditions for correlation studies to be found in southern Nevada. Mesquite Valley: The general situation in the Mesquite Valley is very similar to that in the Pahramp Valley except for the absence of the large springs and flowing wells. A very large area with a water table close to the surface in and adjacent to the Mesquite Lake from which ground water discharge is taking place takes care of the comparatively small annual increment very nicely. No leakage into any of the surrounding valleys appears likely. Indian Springs Valley: It is believed that an underground outlet must exist for tne Indian Spri:igs Valley. The watershed area is large with a fairly large percentage of high mountain so the average annual increment of water must be considerable. The water table under the main part of the large dry lake lies better than 60 feet below the surface which precludes the possibility of any great loss from evaporation. The small flow at Indian Springs and Mesquite Springs cannot account for more than a small part of the total water supply. Two possible outlets appear to exist, namely toward the west into the Ash Meadows or toward the south into the Las Vegas Valley. ESTIMATED ELEVATIONS AND WATER TABLES Indian Springs to Tule Springs Deoth Dep. to water- Dev. Water table elevation Mescuite Sprg. Well------6-00' 2' 3220 3218 Indian Sprg. Valley Well- 700 65' 3073 3000 Alex-nder Well-----------303 301' . 3065 2764 Corn Creek "----------? S7p 11R' - 2S50 2735 Tule Sprg.------------------------------2^7S Dur Well----------------- 75 7^' 2392 2313 The drainage into the Indian Springs Valley is very evident, largely from the high mountains on the south and west toward the north. Water flows at Indian Springs on the south edge of the valley and at Mesquite Springs 4 miles to the northwest. From these points the valley slopes rather gently northward toward toward the large dry lake, tut water table measurements indicate that the water table has a steeper slope in the same direction. If the underground outlet to the dry lake were to the north and west the deep wells at Mesquite Springs should indicate a lower water table than the wells near the center of the valley, but the accompanying profile of the ground and water table conditions indicates a decided drop in the water table from the Mesquite Springs toward the low part of the dry lake. Owens Dry Lake: From the wells in the Indian Springs Dry Lake to the Al- exander Well at the north end of the Owens Dry Lake, the profile of the water table continues with, a rather steep gradient. At this point the water table lies 300 feet below the lake surface, which is quite positive indication of an underground outlet, evaporation from this depth sufficient to take care of even a very small increment being out of the question. Since the water table under the Indian Springs Dry Lake lies at a higher level than it does under this area drainage cannot possibly take place in tne direction of the Indian Springs. Altho no investigation has been made of the Mormon Gulch Dry Lake it does not ap-pear reasonable to expect the drainage from the Owens Dry Lake to be in the direction of this higher lying area, hence apparently the only possible outlet is toward the Las Vegas Valley. Corn Creek Estimates of elevations from tne contour maps and rough measurements of the depth to water in the old Corn Creek Well indicate a slope to the water table from the Alexander well in the Owens Dry Lake toward Corn Creek with a gradient of about 3 feet per mile. The heavy flow the Corn Creek area from Sheep Mountain gives rise to an area of high water table along the south side of this valley where springs and water mounds appear and tends to confuse the general situation regarding the large drainage channel. From the springs at the base of the slope from Sheep Mountain westward to the Railroad Well at Corn Creek Station, where the water stands about 45 feet from the surface and thence westward to the old Corn Creek well where the water table stands about 115 feet from the surface , the water table has a very heavy gradient toward the west. These facts would seem sufficient to warrant the assumption of the presence of a deep, underground channel along the western edge of the Corn Creek Valley into which this area as well as those to the north drain. Tule Springs: Going southward from Corn Creek the gradient of both the ground and water table surfaces increases rapidly until the Tule Springs are reached. Here the underground water table apparently reaches the surface, tho the conditions that give rise to a flow at this point may have little to do with the underground flow from the north. It seems possible that the flows at the Tule Springs are due to seepage from the alluvial slopes of Kyle Canyon which heads far above Charleston Park on Charleston Peak, and the real underground flow may be at a much lower level than the springs. The situation appears to be much like that at Corn Creek. There are no wells in the immediate vicinity of the Tule Springs to assist in locating the actual ground water level. About 2 miles south of the springs is a dug well in which the water stands about 74 feet from the surface. If this be taken as the true water surface and it be assumed that the water table follows an even gradient from the Corn Creek Well to this point it seems probable that the real underground water table lies at least 100 feet below the top of the water mounds at Tule Springs. This calculated line of the water table from Corn Creek to the dug wells shown on the accompanying profile chart as a broken line while the line from Corn Creek to the Tule Springs is shown by the usual solid line. The West Side of Las Vegas Valley: Beginning with the dug well south of the Tule Springs the level of the water table along the west side of the valley has teen pretty definitely established. Level lines have been run from U. S. G. S. benchmarks to practically every well along this edge of the valley and exact elevations determined. Measurements to the water in these well have been carefully made so that the actual water level can be quite accurately determined. The relationship between the ground level and the water table shown on the accompanying sketch map and profiles. The included table gives the data for the various wells on which the profiles are founded. From this information it has been possible to estimate quite closely the probable water level in new wells aIong this line. Ground and. Water Surface Elevations Along west side of the Las Vegas Valley-1931 'Jell Description Depth of Depth to__Hleva tion_ No. and name__Well Water Ground Water Surface ll Dug, 1905? 75.0 y^.y, 2302.1 2118 4 2. Drilled, 1?29, Engler 121.0 ^ glS.4 3. Synd. Sec. 10, drilled, 1511,^.^^00.0 52 ^ 2*^07 0 22*4 7 4. Smoke, drilled 1915? ^ 265.O ' [G 2225^6 222^0 5. Taylor dry well, anllea, 315. 19.0 2244.0 2225 0 6. Taylor R?nch, drilled, 1922 315. 2216.^ 7. Kidder, drilled 1925 354. 13.2 2226^2 2215.0 g. Mc Williams, drilled I03O 308.. 14.9 222^.8 2214 ? 9. Depdrich, dtilled, 191o 280. 22.0 2225.8 2203*.^ 10. De Juli.n drilled 1^1 331. ^25 21b7.2 2lG6!o 11. Milaren, drilled, 1930 310. 28.0 21C0.6 2162 ^ 13. FrpnkBe^m, drilled, 1^51 113. 01.3 2214.5 14. Pat Gaucher, drilled, 1930 ^o. S5.O 2242.2 2157 2 15. Mrs. Johnson, drilled, 1930 113. ^-3.6 12. Careyact, drilled 1O10, dept. ,50. ' j^g ^57-2 originally 55O' A similar relationship between ground levels and the water pressure . levels for a series of flowir. wells is now being worked up. In general a definite slope to the water surface from north by northwest to south by southeast is clearly shown. The natural inference from this fact is that the strong flow of water is from the north and west. However a free outlet at the south end if the valley would accomplish the same result, but the presence of such an outlet would be evidenced by large flows of ater. Since the large flows are not present in this part of the valley and are present farther north we may properly conclude that the larger increment of water is from the northn and west. Further supporting evidence of this assumption is given in the character of the soil and hardpan in the north and south sections of the valley and in character of the water as shown by chemical analyses. North of the station of Bracken the soil contains comparatively little gypsum but does contain much lime, and over the whole of the area of flowing water is a caliche hardpan which has been formed by the evaporation of lime charged waters. South of Bracken large areas of gypsum take the place of the cal-iche, indicating the evaporation of waters high in calcium sulfate. Analyses of water shown in the table below indicate a lime carbonate water of low concentration in the north with a gradually increasing concentr tion and a slow changing to a lime sulfate character in the waters to the south. This accords well with the character of the hills forming the watershed in the two parts of the valley, the hills to the north being composed largely of dolometic limestone while to the south immense deposits of gypsum lie against the east face of the limestone. These assumptions permit the inclusion of the drainage from the whole area north to Indian Springs since these waters are quite similar in chemical character and concentration to those in the north end of the Las Vegas Valley. Likewise the waters of the Ivanpah Valley could easily pass with the waters of the south end of tne Las Vegas Valey, comparing quite well ir chemical character and concentration. The relation of this dry lake to the Las Vegas Valley will be considered next. Analyses of waters from the Indian Springs, Corn Creek Springs, Tule Springs, west side of Las Vegas,Valley , and Ivanpah Valley Constituents in parts per million Indian Springs Valley Si02 Ca Llg Na HCO3 SO4 CI Total 'K' Quality for use Source of Solids Domestic Irrigation Information Indian Springs 17 48 15 31 239 28 5 330 40 good Good s..S.P. 365 Ira HcFarland Well 17 56 26 tr 269 19 20 263 102 tt tt W.SP. 3 65 Tim Harnady Well ND 57 38 26 325 60 21 362 82.5 tt tt Nev. Exp. Sta. Corn Creek Spring 18 54 28 17 292 26 12 287 140 Good Good W.S.P. 365 Tula Spring ND 52 28 19 255 27 86 207 237 Ccod Good Ney Exp. Sta. Las Vegas Valley from North to South Eglington Well 17 57 32 ? 249 41 9.3 208 220 Good Cood Nev. Exp. Sta. Las Vegas Spring 12 58 25 17 259 48 18 291 104 tt tt Pub. H. Lab. Dr. Park Well (in city) 8 54 25 10 251 39 10 318 185 H tt W.S.P. 365 Bryant Well 16 68 32 12 243 109 10 329 65 Fair tt Nev. Exp.pSta. Li Idren Well 19 81 25 31 245 148 12 410 105 tt tt tt tt tt Cottonwood Spring 19 102 43 46 290 146 11 563 90 H tt W.S.P. 365 Pittman Well ND 116 39 42 168 358 22 745 66 tt tt I-.ev. Exp. Sta. KcGriff Well 30 166 55 57 220 479 64 1003 30 Poor tt Nev. hxp. Sta. Ivanpah Valley Ivanpah- R. R. Well 17 26 4 49 73 73:.. 35 240 47 Good Good W.SP. 450 R. Buchner Well 41 15 5 101 171 31 61 372 99 tt tt Desert Sta. R.R. Well 17 26 19 107 154 49 139 433 14 w Fair Note- Sodium appears to be the most variable constituent in desert waters, analyses of samples of water from the same source taken at varying intervals showing wide variation in the percentage of this element present. The Ivanpah Valley: This dry lake is almost completely surrounded by Iow hills, reaching a fair height in Mt. McCullough, and altho the total area of the watershed is quite large the runoff is undoubtedly light and the annual increment to the underground water supply is ouite small. Nevertheless if the valley were a tight basin the everage annual increment '.s sufficient to fill the sediments in the valley and bring the water table close enough to the surface to permit evaporation. However under the main part of the dry lake where the water table is nearest the surface it is from 80 to 100 feet to water, which in the absence of deep rooted trees like the mesquite precludes the possibility of mucn loss of moisture by evaporation. There seems to be no possible escape for the waters of this valley to the west because the areas of ground water discharge in this direction are at higher elevations than the water table in tne Ivanpah Valley. On the north the water table under the surface of Mesquite Lake is some 15 feet higher than that under tne Ivanpah Valley. so drainage in that direction is apparently impossible. This leaves the Las Vegas Valley as the only probable outlet. If the Ivanpah Valley be assumed to be a structural trough or canyon it takes very little imigination to consider the fault structure as extending north-eastward, to the Las Vegas Valley. Indeed the valley thru wh.ch the Arrowhead Trail highway and t..e Union Pacific Rail Road run from Jean to Sloan has every aopearence of being a fault. If this is indeed the case there wojld be every opportunity for the escape of the Ivanpah Valley waters thru the coarse material v.nich probably fills the lower part of this valley. With tuere propositions in ::.j,nd consider the ^rndier.t of the ..round water table under the Ivanpah dry lake as shown on t..a accompanying map 'nd n-ofile. The data used in constructing this c:r rt -re in some in- stances estimates, and in others are t? ken from data collected several years age. When time permits the data on these wells should be recheck- 1 ed. It will be noted th<*t the water table slopes very gradually but quite conclusively toward the north and east, that is toward the Las Vegas Valley. Ground and "?ater Surface Elevations Along Center Line of the Ivanpah Valley, Nev.-Calif. 1931 Well No. Description and Name _Deoth_ __Elev-- tion_ of 'well to water Ground 7/ater 1.1. R. R. Ivanpah pumping sta. 530 370 2922 2552 2. Murphy, dug, tile casing llo 92 2ol7 2p2p y 3. Ruben Buckner drilled 4l2 38 2ol2 2524 4. San Francis dug 02 90 2615 2525 5. Chris Mattley, drilled two wells 120 84 2600 26lo (M water 32y to S^ feet) 6. A. E. Weaber, drilled 120 37 2602 2515 7. A*. Dixon " . 120 79 25% 2519 S. Roy White " . . SS 77 2595 2513 9. R. R. Desert well, (Lyons Sta.) 506 275 2S00 2525 ^10. S. E. Yates dw: . 91 31 259S 2517 ' 11. Borax Team. Well dug 92 90 2ol0 2520 12. Geo. Morgan drilled 91 91 2oOS 2517 13. R. R. Borax Siding 6S7 199 2703 2504 Dave Farnsworth, Jean 520 3^5 234g 2503 There is a well at Sloan at an approximate elevation of 2350 feet in which the v.ater is reported to stand about 400 feet from the surface, which, if true, accords cuite well with the theory of an underground ^ flow thru this valley. Chemical the waters of the Ivanpah Valley rank with those from the south end of the Las Vegas Valley, differing in a slightly higher proportion of sodium. In this connection it may be pointed out that the waters of t.h so at. end of the Las Vegas Valley are proportionately higher in solium then thos fa tl.er nortu rni th- t this higher concenValley. v,,..--^ n - close correlation between the annu.-l Further Consir.ei" .ion of Factors in tl.a increment fror the oreci )it- tion on t e 1- s V^- - V ile- ' * .. ___ watershed and the discharge in t..i vlley it is necess^-ra- t.rt ^n the points of discharge shouH be mov.n and. the flov.-s measurcble. A discharge thi*u deep lying strata into drainage channels outside the valleywould normally be unmeasurable, and w uld render the data on other measure...ents subject to doubt. It is my belief that the Las Vegas Valley* is a very tight, closed casin with little chance of any lose thru the deep lying strata, and th-t all the Incoming waters are taken care of in the valley. Some water from the storms is lost at once thru direct runoff over the surface and out thru the Las Vegas Wash. However the water that gets into the-deep lying strata is all brought back to the surface where it apnears as springs or flowing wells or as areas of high v;ater table where ground water discharge takes place. These various means appear sufficient to take care of the average annual increment into the valley. Several factors support this view. The sediments filling the lower part of the valley are older than the present Colorado River drainage and ware laid 'own pres^mr^le in a closed basin during arid, conditions. That the climate was arid is shown by the abundance of gypsum crystal? found in the drill cuttings in wells sunk thru these old clay beds in the extreme low part of the v lley. The material in the water bear-in;.' beds grows progressively finer from the western m-rgin of the valley toward the center, and finally appear to feather out as the extreme low part of the valley is reached. No large flows appear in the course of the Las Vegas Wash --fter it leaves the valley altho the wash cuts thru heavy, intrusive rocks th"t would normally be expected to almost certainly bring the water fro::, the deep lying strata to the surface. . The small flows developed are confined entirely to the sur- fac. ,r.- vels in t.n ?.asi., and represent tne dr--ir.a_,e or w""sta e from * the artesian flows in tht valley plus a small part of the storm waters tu-t fin's its w"" into the stream ravels. Hot all the water discharged in tne Las Vegas Valley is meas.u--able directly as flowing water. A part rust be estimated from the area of ground water discharge and the growth of the water tolerating plants as mesquite, all^li grass, tules, etc. However with an increase in the amount of water pumped in t.'.e low valley the water table in this area may be expected to drop, with a consequent lessening of the ground water discharge. As time passes it should be more nearly possible to measure directly all the discggge in t:.e Las Vegas Valley. The Las Vegas Valley is a closed basin in so far Recapitula tion as the artesian waters are concerned and all the incomin water can be measured directly as flows or indirectly thru the ereas of ground water discharge. The source of the water lies in the Charleston and other mountains tin t surround the valley. The under ground, drainage from the Indian Springs, Owens Dry Lake, and Mormon Gulch to the north, and the Ivanpah Valley to the southwest prob-ably discharges into the Las Vegas Valley. These areas would necessarily enter into any complete study of the water supply of the Las Vegas Valley. The Pahrump, Mesquite and. Ash Meadows ereas are separate units not connected in any way with the drainage of the Las Vegas Valley. The watershed area contributing directly to the Las Vegas Valley totals about 632 square miles in the Las Vegas , Sheep, and Charleston Ranges. The total watershed area contributing to the Las Vegas, Indian Springs, Owens Dry Lake, Mormon Gulch, and Ivanpah Valleys compirises about 1866 square miles. The Charleston Park watershed has about 105 square miles between the 3$00 foot contour - ad the to - of Charleston Peak. t The distance "round the Charleston Range by -uto ro"d is about <- 'J mules. Each side road leading up toward tne top of the moun- tain, of which there ere about 7. is about 25 miles long, so a complete circuit of the mountain with trips to eac. of the important parts of the watershed would entail about 5OO miles travel. This would not include the Ivanpah Valley, 53 to 75 miles away. The Charleston Park area offers a fair section of the watershed wnich mi <ht be studied intensively. It is readily accessible at elevations from 3500 to 8503 feet, witn foot travel possible to the top of the peak. Snow courses would be most accessible in the area. A complete study of the whole watershed would entail considerable expenditures for ecuipment and travel over several years. The cost of Charleston Park studies would by only a small'part-of that necessary for the total watershed, and the data gathered on precipitation mi ht be aoplied in oart at least to .other sections of the -watershed. Submitted Larch 27, 1931 George Hardman, Chief, Dept. of Irrig.& Agron.