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<br />River Regulation <br /> <br /> <br />Water levels in all of the major reservoirs <br />were lower in water year 1985 than in <br />1984. This was partially due to lower <br />Inflow as well as elevation restrictions on <br />several Upper Basin reservoirs. Tile <br />natural runoff of Ihe Colorado River <br />drainage during 1985 at Lee Ferry, <br />Arizona, was estimated to be 20.8 mal. <br />Of this amount, about 3.3 mat was <br />consumptively used in the Upper Colorado <br />River Basin Stales. <br /> <br />Adjusting for regulation 01 Upper Basin <br />reservoirs resulted in an unregulated <br />inflow to Lake Powell of 17.5 maf durrng <br />water year 1985. Annual releases from <br />Powell based on stream gaging records <br />at Lees Ferry, Arizona, was 19.30 mal, <br />For Ihe l'year and 10-year periods ending <br /> <br />September 30, 1985, 19.3 maf and 118.8 <br />maf, respectively, passed the compact <br />pOint at Lee Ferry including the average <br />annual discharge of the Paria River at <br />Lees Ferry. <br /> <br />The projected water year 1986 release <br />trom Lake Powell, based on reasonabte <br />minimum runoff conditions is 8.7 mat. <br />The projected releases for the reasonable <br />maximum runoff condition is 16.1 maf as <br />of November 4, 1985. <br /> <br />Daily releases are made from the storage <br />reservoirs in the Lower Basin to meet fhe <br />incoming orders ot. the water user <br />agencies. When possible, all water <br />passes through the powerplant units. The <br />daily releases are regulated on an hourly <br />basis to meet as nearly as possible the <br /> <br /> <br />Rough Waler Boating on the Coloraoo <br /> <br />22 <br /> <br />power loads of the hydroelectric power <br />customers. Minimum daily flow Objectives <br />are provided In the river to maintain <br />fishery habitat. <br /> <br />The combination of high runoff conditions <br />and river regulation below Hoover Dam <br />resulted in a total delivery to Mexico 01 <br />approximately 11,530,000 acre. feet in <br />excess of the scheduled treaty quantity <br />(1,700,000 acre-feet) during water year <br />1985. Of that amount, 130,600 acre-feet <br />of drainage waters ,were bypassed to the <br />Gulf of California via the Bypass Drain. <br />This bypass channel was constructed <br />pursuant to provisions of Minute No. 242 <br />of Ihe International Boundary and Water <br />Commission. <br /> <br />The most probable water supply <br />operation will yield 6.3 mal of effective <br />flood control space on January 1, 1986. <br />With 6.3 maf 01 effeclive space it is <br />virtually assured that flood control <br />releases from Hoover Dam 01 at least <br />19,000 cfs will be required during water <br />year 1986. <br />