Report by Moapa Soil Conservation District on irrigation storage possibilities of Wells Siding, Bowman Reservoir, and adjacent basins, December 1944

MOAPA SOIL CONSERVATION DISTRICT IRRIGATION STORAGE POSSIBLITIES December 1944 This report contains the results of a preliminary survey which been made for the purpose of preliminary evaluation of the irrigation storage potentialities feasibility of storing, various volumes of irrigation water at these sites, four optional degrees of development were considered, Item of construction required, estimated costs, storage capacities, and descriptions of each alternate proposal were determined and tabulated. See Table I attached. In addition, cursory study was made of the problem of obtaining sufficient storage capacity at these sites to permit maximum utilization of all lower valley water resources. The findings of this study are described in narrative form herein. The results contained in Table I attached were obtained by the following method: A topographic map was prepared of the Bowman Reservoir and small adjacent basins. The area between Wells Siding dan and Bowman Reservoir which would be traversed by any new and higher supply conduit between these points was also No topography was taken upstream from Wells Siding dam. The capacities of the storage units at various water surface elevations were determined with considerable under option 4 was estimated. The quantities of construction materials and work involved in the various optional developments were determined from "paper" locations on this topographic map. No detailed plans or ground locations were made. Total costs were calculated by applying current (December, 1944) unit construction prices to the preliminary quantities of material and work thus estimated as being required. It should be obvious at this point that the information in table I is appropriate only for use in evaluating the several optional developments listed therein and not for the final evaluation of the economic feasibility of developing this storage site as compared to other possible storage sites. Geological conditions were not considered in any detail in the survey covered by this report. The final feasibility of all the developments considered herein is contingent upon the existence of satisfactory geological conditions in the area concerned. Information from various sources indicates that approximately 5,000 acre feet of storage capacity is required for maximum utilisation of all lower valley water resources. The practicability of storing this volume of water in the sites covered by this study is questionable. The ultimate capacity of Bowman Reservoir and adjacent basins is definitely limited, and storage of irritation water on the Muddy River itself, in the vicinity of the present Wells Siding ?Prepared by Ellis L. Katt, Soil Conservation Service . 2 - diversion structure at least, is certain to involve very high costs. Any significant increase in the maximum water surface elevation upstream from the present Wells Siding Dam above that considered in development Option 4 (5 foot raise) will require major alteration or replacement of the existing structure, and a relocation or raising of a considserable length of the Union Pacific Railroad grade. Preliminary studies of alternate designs for the supply conduit between the present Wells Siding Dam and Bowman Reservoir indicate that the probable Bowman Reservoir water level. However, no estimates were tabulated for supply conduits capable of delivering water to Bowman Reservoir at higher elevations than the maximum established for development option Upstream flood oontrol is a prerequisite to the continued successful operation of any storage reservoir which might be located on the Muddy River downstream from the confluence of that stream with Meadow Valley Wash. Flood control details were not considered in the study covered by this report. It is believed, however, that construction of facilities adequate to eliminate the siltation hazard from a storage reservoir on the lower Muddy River would be very expensive. Since the investigation reported herein was both preliminary and incomplete, no definite recommendation can be made in this report regarding the practicability studied. TABLE I ITEMS OF CONSTRUCTION, ESTIMATED COST 1/ AND CAPACITIES FOR FOUR DEGREES OF DEVELOPMENT OF THE BOWMAN-WELLS SIDING S STORAGE SYSTEM (1) Items of Construction Required Install additional outlet capacity - Bowman Dam Option X al Degr* X ses of I 7 X ? S 2 S * X (2) Solve seepage problem - Bowman Reservoir X X X X (3) Raise earth dike - Bowman Dam X X X 0 0 Raise spillway - Bow .on Reservoir X X X (5) Construct and/or revise oonduit Wells Siding to Bowman Reservoir X X (6) Install automatic release gates in primary spillway Wells Siding Dim. X 1^/Total Estimated Cost (Approx,), Dollars Total Capacity, Aore Feet Ap rox. Cost Per Acre Foot, Dollars $14150 1380 % 3 |8200 &j6,000 $92,000. . 1600 1,950 2,8ooar $5?lo 323.60 #32.90 quantities of construction work. No detailed plans were prepared. 2/ Option description Option 1. This alternate represents the present status of diversion dam, the supply conduit, and the storage dam and spillway. Full use of the existing facilities for irrigation storage purposes requires the of some tile to protect lands below the dam from the ill effects of seepage Option 2. The largest storage development permissable without relocation of the existing supply channel between Wells Siding Dam and Bowman Reservoir is represented by this option. Bowman Reservoir maximum water surface elevation 1428.03 is one foot below the bottom of the stringers of the existing State Highway bridge over the so-called flood channel, between Wells Siding Dam and Bowman Reservoir - 2 - Option 3. This option represents about the largest storage development possible without any change in the existing Wells Siding Diversion Dam. The flow line elevation of the existing masonry spillway at Wells Siding is 1433.2. The maximum water surface elevation in Bowman Reservoir under this alternate is 1431.0. Option 4. This alternate requires a five foot raise (to elevation 1438.2) in the maximum water surface elevation above the Wells Siding Diversion Dam. Since the flow line elevation of the emergency (west side) spillway of the existing diversion structure is approximately five feet higher than the flow line level of this structure's primary spillway, this alternate represents about the maximum storage obtainable without major alteration of the present Wells Siding Dam. 3/ All elevations are based on U.S.C. and G. S. datum. 4/ Usable capacity of Wells Siding Dam at elevation 1438.3 (estimated at 200 acre feet).