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.WATER UNITED STATES DEPARTMENT of the INTERIOR *********************news release ~ O' '(d'Y ~~"" /J tl ~ BUREAU OF IUX:U.MATION S ,(; Williams - 343- 4662 For Release JULY 4, 1965 FEATURE MATERIAL NF.\Y RIDULATING RESERVOIR WILL HELP RECLAMATION IMPROVE WATER DELIVERY SCHEDULES ON LOWER COLORADO RIVER The Bureau ot'"ileclamat1.on' s job as ~he Nation's largest watermaster will be made easier on the Lower Colorado River near the Mexican border by a small off-stream pumped-storage project now under constr uction. The new reservoir will assure more accurate deliveries to users in the United States and Mexico while simultaneously saving substantial quantities of water. Reclamation engineers in the Department of the Interior have devised a way to sidetrack temporarily flows of the Colorado River above Imperial Dem, 18 miles upstream from Yuma, Ariz., when not needed and later release the water back to the river for downstream use. This will improve water scheduling and eliminate many uncertainties in dispatching. Commissioner of Reclamation Floyd E. Dominy said the sidetracking will be accomplished at Senator Wash Dam and Regulating Reservoir on the California side of the river two miles upstream from Imperial Dam . This small off-stream -pumped­ storage project at the river-end of Senator Wash gets its name from tbe abandoned Senator Mine . Senator Wash Dam and Regulating Reservoir, scheduled for operation early in 1966, will give Reclamation's river-control engineers more flexibility in dis~ patching water while salvaging 170,000 acre- feet or more each yeo;:. It will permit water to be pumped out of the river at Imperial Dam and to be returned later to help meet irrigation requirements in California, Arizoua, and llexico. This salvage of water will be possible even though Senator Wash Regulating Reser­ voir will have a stor age capacity of only lJ,400 acre-feet. Commissioner Dominy expla5.ned that Senator Wash Dam and Regulating Reservoir will provide conservation benefits totaling nearly $5t million a year. Although hydroelectric power will be valued at only $11,000 a year, this income will help offset the cost of pumping water from the river into the reservoir. The dual­ purpose pump-generating plant will have a generating capacity of 7,200 kilowatts. The Bureau of Rec lamation's Region J, through its Lower Colorado River Control Office, has been dispatchi.ng water to users below Hoover Dam since late in 1944. Accurate control of water since has become increasingly important in both the upper and lower basins because it has become more difficult to meet all the multipurpose requirements from the limited supply of the river. Water sched­ uling procedures have been refined. In recent years the releases at Hoover Dam-­ ·• all of which flow through Hoover Powerplant turbines to generate hydroelectric energy--have been restricted to that water needed to meet downstream requirements. As water in the Lower Colorado River has become more limited, difficulties have developed in deliverJ.ng..at-Cthe right ~ime& the right amounts ordered by the users . The problem centers on the fact that the released water must travel long distances before reaching the user. When water released at Hoover Dam reaches its farthest point on the All- An:erican Canal System in the Coachella Valley of southern California it has t raveled nearly 5(X) miles and has required 10 days to make the trip. The Bureau of Reclamation releases water from storage for delivery to 16 separate agencies below Hoover Dem for irrigation, municipal and industrial use. Thirteen of these agencies divert at or below Imperial Dam, a little over JOO miles down river from Hoover Dam. In scheduling the release of water, several determinations must be made: the needs of all water users, the losses to water-consuming needs, to evaporation, and t o seepage. The daily change in the reservoirs at Davis Dam and Parker Dam also must be considered. Irrigation projects also must collect considerable informa­ tion before their water orders can be submitted. They must learn from each farmer what his needs will be over a period of several days . These requirements often change because of a sudden rainfall or very hot weather. Water orders are relayed to the Bureau of Reclamation each week by telephone, teletype, or radio, giving rates at which irrigation water is desired for every day of the following week. All these orders, when consolidated, permt...Reclama­ tion dispatchers to begin scheduling the release from the various dams . Imperial Dam is a low diversion dam with limited storage capacity in its reservoir. Thus, it is capable of providing only minor regulation to assist in diversion operations. Parker Dam, 148 miles upstream from Imperial Dam, is the last major storage and control point on the Lower Colorado River. Water must be released from Parker Dam three days before its scheduled arrival at Imperial Dam . At present, when water is released at Parker Dam it is on its way--it cannot be recalled, stopped, or stored. From five to seven days are required to reach headgates in Coachella Valley--about four days to fill orders in the Wellton-Mohawk Valley in Arizona . All other irrigated areas on the lower end of the river similarly must 2 wait from three to four days. And although Yie Bureau of Reclamation has developed an effective and efficient dispatching procedure, it is impossible, even under the best conditions, with existing facilities to control fully the flows to meet diversion requirements without overdeliveries or shortages. Additionally, the vagaries of weather add to the complexities of normal river .,... operation. These include unexpected rises or drops in temperature, changes in humidity, rainstorms or unpredicted cloudbursts that occur after the scheduled ,I,. water has been released at Parker Dam. The farmer might call for more or less water than he had ordered. In case of rain, for example, he would need less and if the temperature rises he might need more . Shortages may be compensated by further deliveries on subsequent days. Conversel¥, when flows exceed-<iiversion requirements, those which cannot be used or temporarily stored in the limited operating space in Imperial Res ervoir must necessarily be released to the river in addition to Mexico's Treaty requirements. Such losses cannot be accepted under conditions of restricted supply and high demand now experienced in the Lower Colorado River Basin, Commissioner Dominy said. When Senator Wash Regulating Reservoir goes into operation it will be possible to eliminate almost all the overdeliveries and shortages. Excess water arriving at Imperial Dam over the scheduled amount will be pumped out of the river into the new off-channel regulating reservoir and shortages in the river flow can be augmented by releases from the reservoir through the same dual-purpose pumping-generating plant. Unexpected changes in irrigation requirements result­ ing from changes in the weather or other factors can al so be accommodated up to the capacity of the plant by pumping unneeded water into the reservoir or releas­ ing water from the reservoir. Normally, the reservoir will be held at approxi- .. mately one-half its available capacity to permit either pumping or discharge of water, as required. Commissioner Dominy said that although Senator Wash Dem and Regulating Reservoir will insure greater flexibility in operations on the Lower Colorado River, the cost of pumping water into the reservoir "dictates that every effort be continued by the irrigation districts and the Bureau of Reclamation to continue to schedule water requirements i n a most prudent end realistic manner·•-lreeping operations at Senatr>r Wash to a minimum." > The full. value of this off-stream reservoir for recreational purposes will not be known until the pattern of reservoir operations is established by actual use. Because the primary purpose of the reservoir is t o reregulate river flows, its level will vary. However, Reclamation officials anticipate that once the reservoir is created it will be in heavy demand for water sports. The Bureau plans construction of a boat-launching ramp that will function at all water stages. J As to additional recreational uses end fish end wildlife enhancement, Colmlissioner Dominy said the Bureau will work with other Federal agencies and State and local groups in developing the reservoir for these secondary purposes. How­ ever, it is not possible for the Bureau to guarantee maintenance of the reservoir at specific levels or assume any responsibility for the effects of the project's operation on nonproject activities, he emphasized. Senator Wash Dam and Regulating Reservoir will cost about $8! million. A feature of the Bureau of Reclamation's Colorado River Front Work and Levee System Project, it has been under construction by M. M. Sundt Construction Company of Tucson, Ariz., since February 1964. Major features include the 85-foot high, 2,100-foot long earthfill dam, three dikes, a reversible pump-generating plant, and related works. xx x P.N. 65J45-65 4 10 days from Hoover Dam to Coachella Valley's farthest point. 3 days from Parker Dam to Imperial Dam . .,• 5 to 7 days from Parker Dam to Coachella Valley. 4 days from Parker Dam to Welton-Mohawk Division, Gila Project. DAVIS DAM 3 to 4 days from Parker Dam to Yum a Valley and Yuma Mesa.---Oivision. 4 to 5 days from Parker Dam to Imperial Valley. PALO VERDE DIVERSION DAM IMPERIAL DAM •• AII -Amerlc111 Ca1a l 'l'i......A\VE LTON -MOHAWK DIVI S ION .

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