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<br />In addition to the users listed on Table 6, mis-
<br />cellaneous users divert from Colorado River or
<br />pump from wells adjacent to the mainstream.
<br />Gross diversions of these miscellaneous users ill
<br />California, Arizona and Nevada have amounted
<br />to more than 100,000 acre-feet a year for the past
<br />several years,
<br />The Bureau of Reclamation releases water at
<br />Hoover Dam to satisfy requirements for the
<br />Mexican \V ater Treaty and sixteen separate
<br />agencies in the United States; thirteen of the
<br />agencies are served by diversions at Imperial
<br />Dam. Parker Dam, 148 miles upstream and three
<br />days' flow time from Imperial Dam, is the near-
<br />est major regulating srructure. Many factors are
<br />involved in scheduling releases to meet antici-
<br />pated downstream requirements. The rate of
<br />flow at Imperial Dam is seldom the precise rate
<br />actually required owing to changes in the
<br />weather and other factors, during the travel time
<br />from Parker Dam. Minor shortages can some-
<br />times be compensated for by increased deliveries
<br />on subsequent days, Plate 7 shows the periods of
<br />time required for Parker Dam releases to reach
<br />various agriculmral areas.
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<br />Deliveries to Mexico
<br />
<br />In January 1966 the Bureau of Reclamation
<br />completed construction of Senator Wash Dam
<br />and Regulating Reservoir, on a tributary wash
<br />in California upstream from Imperial Dam.
<br />However, operation was on a limited basis during
<br />the remainder of 1966. Excessive wear was ex-
<br />perienced in much of the pumping machinery
<br />and extensive repairs were made by the manu-
<br />facturer prior to placing the project in full use
<br />early in 1967.
<br />Senator \Vash Dam and Regulating Reservoir
<br />was formally dedicated on the afternoon of April
<br />20, 1967, bv Secretary of the Interior Stewart
<br />L Udall. . .
<br />The dam is an earth fill embankment 94 feet
<br />high and 2,340 feet long. The dam and three
<br />dikes create a reservoir with a capacit), of 13,800
<br />acre-feet. The reversible dual-purpose plant has
<br />a pumping capability of 990 cfs and generating
<br />capacity of 7,200 kilowatts. The plant is oper-
<br />ated by remote control from Imperial Dam
<br />where the Bureau of Reclamation has an operator
<br />on duty around the clock.
<br />Senator "1 ash Pumping Plant commences
<br />pumping water from Imperial Reservoir to Sena-
<br />
<br />tor Wash Reservoir whenever surplus wat~r
<br />reaches Imperial Reservoir. Concurrently, if Sen-
<br />ator V>'ash Reservoir contains more than 5,000
<br />acre-feet of water, releases from Parker Dam are
<br />reduced. As a precautionary measure, because of
<br />the three days required for Parker releases to
<br />reach Imperial Dam, releases from Parker Dam
<br />arc not reduced if Senator Wash Reservoir con-
<br />tains less than 5,000 acre-feet. If the available
<br />river flow to Imperial Dam is less than water
<br />requirements, the flow is augmented by releases
<br />from Senator \Vash Reservoir,
<br />
<br />The Bureau of Reclamation maintains a "con-
<br />trol schedule" which includes the scheduled de-
<br />liveries to Mexico plus releases from storage for
<br />sluicing, river regulation and other purposes. The
<br />scheduled deliveries, control schedules and ex-
<br />cess deliveries to Mexico for recent vears are
<br />shown in Table 7. .
<br />
<br />Table 7
<br />DELIVERIES TO MEXICO-COLORADO RIVER SYSTEM
<br />(Thousands of Acre-feel)
<br />
<br /> Total EXCOJ
<br /> Sdltdu/ed EX(fSJ 0",
<br />Waler D...firu,.jes Confrol Flow D...lirJerieJ Control
<br />Yfar to AIt'xjeo Schedule to Mexico to Meo'deo Schedule
<br />1962..m_ 1,500 1,540 1,763 263 223
<br />1963.. ~ ___ 1,500 1,873 2,113 613 240
<br />1964...... 1,500 I,S49 1,776 276 227
<br />1965..m_ 1474 1,502 1,594 120 92
<br />1966_..m 1'541 1,632 1,720 179 88
<br />1967_..m 1:459 1,517 1,566 107 49
<br />
<br />Plate 8 shows deliveries to Mexico by years
<br />from 1951 through 1967, and Plate 9 sho,,:s the
<br />same information by days for the water year
<br />1966-67. The improvement in control afforded
<br />by the Senator Wash Project can be judged by
<br />comparison of the total excess deliveries to Mex-
<br />ico in 1967 with the excess for 1965 and 1966,
<br />as shown in Table 7.
<br />
<br />During most months of calendar year 1967 the
<br />unavoidable excess arrivals of water at the bound-
<br />aty, i.e" excess arrivals not caused by Minute 218
<br />of the International Boundarv and '\Vater Com-
<br />mission, were remarkably lo,v. By deducting a
<br />roughly estimated but substantial amount for un-
<br />controlled stonn runoff below Imperial Dam in
<br />September, the total of such unavoidable excess
<br />arrivals may be approximated at about 10,000
<br />acre-feet, or less than 0.7 percent of the sched-
<br />uled flow for the year. The minimum monthly
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