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<br />\I \l . .. <br /> <br />c.f.s. are maintained. Under more normal conditions when storage levels <br /> <br /> <br />are adequate, a winter release rate of 15,000 c.f.s. from Fort Randall <br /> <br />Dam is scheduled. If reserve storage is low, as little as 5,000 c.f.s. <br /> <br />is released from Fort Randall Dam. <br /> <br />Because of the large amount of storage, uncontrolled releases from <br /> <br /> <br />the main stem reservoirs are quite rare. Essentially all water is used <br /> <br /> <br />to serve system functions as indicated by the following summary of <br /> <br /> <br />existing release requirements. <br /> <br />Navigation Season Releases (Full Service) <br />8 months @ 35,000 c.f.s. = 16.9 MAFA <br /> <br />Nonnavigation Releases <br />4 months @ 16,500 c.f.s. = 4.0 MAFA <br />Total 20.9 MAFA <br /> <br />The above discharges represent approximate average releases from the <br /> <br /> <br />main stem reservoir system that are needed for the reach between Gavins <br /> <br /> <br />Point Dam and Kansas City. Requirements in a given year vary depending <br /> <br /> <br />on downstream tributary contributions. The total release compares with <br /> <br /> <br />a long-term average flow of 21.7 MAFA at Sioux City (adjusted to 1975 <br /> <br /> <br />development level), leaving an average surplus of about 800,000 AFA. <br /> <br />At Fort Randall Dam, operational studies confirm that very little <br /> <br /> <br />surplus flow exists without a trade-off of existing functions and <br /> <br /> <br />values of the river system. In fact, if projections of future in-basin <br /> <br /> <br />development prove correct, the 800,000 AFA surplus currently available <br /> <br />will be depleted before the year 2000. Furthermore, sufficient deple- <br /> <br /> <br />tions would significantly disrupt navigation without any transfers of <br /> <br /> <br />water outside the region by the year 2020. Current estimates indicate <br /> <br /> <br />that additional depletions of 2.3 MAFA upstream from Sioux City and 6.5 <br /> <br />MAFA upstream from the mouth over the present levels would occur by the <br /> <br />A16 <br />