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<br />River Regulation <br /> <br /> <br />Senator Wash Oem and Reeervolr. <br /> <br />Water levels In nearly all of the major <br />reservoirs In the Colorado River basin reached <br />their highest elevatIons since these dams were <br />constructed. The natural virgin runoff <br />reaching the strearTlS of the Colorado River <br />drainage system above Glen Canyon Oam <br />during water year 1983 was estimated at about <br />23.9 mil/Ion acre-Ieet. 01 this amount, <br />approximately 3.7 million acre-feet were <br />consumptively used within the Upper <br />Colorado River Basin States. <br /> <br />Adjustments In storage In main stem <br />reservoirs resulted In an Inflow to Lake Powell <br />of 20.3 million acre-feet. The release from <br />Glen Canyon Dam, based-an.measurements at <br />the gaging station at lees Ferry, Arizona, was <br />17.4 millIon acre-feet. For the 1-year and <br />10-year periods ending September 30, 1983, <br />17,437,000 acre-feet and 95,975,000 acre-feet, <br />respectively, passed the compact pOint at Lee <br />Ferry. <br /> <br />The projected water year 1984 release from <br />Lake Powell, based on most adverse runoff <br />condlllons Is 10,300,000 acre-feet. The <br />projected release for an upper quartile runoff <br />condition Is 15,850,000 acre-feet. When <br />added to the flow of the Parla River, this <br />would result In an upper Basin delivery <br />ranging from 98.0 to t03.5 million acre-feet <br />for the 10-year period ending September 30, <br />1984. <br /> <br />22 <br /> <br />Dally releases are made from the storage <br />reservoirs In the Lower Basin to meet the <br />Incoming orders of the water user agenc\s9. <br />When possible, all water pass.sthrough the <br />powerplant units. The dally reless8s are <br />regulated on an hourly basis to meet 8a nearly <br />as possible the power loads of the electric <br />powercuslomers. Minimum dally flow <br />objectives are provided In the river to <br />maintain Ilshery habitat. <br /> <br />A combination of high runoff conditions and <br />river regulation below Hoover Dam resulted In <br />a total delivery to Mexico of approximately <br />8,080,000 acre-Ieet In excess of the scheduled <br />treaty quantity {1 ,700,000 acre-t..t),durln9 <br />water yeer 1983. 01 thatamount,189,800 <br />acre--feet of drainage waters were bypassed <br />for salinity control pursuant to provisions of <br />Minute No. 242 of the Commission. <br /> <br />Flood Control <br /> <br /> <br />The reservoirs within the basin received far <br />greater total Inflow than durIng normal years. <br />In the Upper Basin, Nava)o and Blue Mesa <br />Reservoirs are operated for flood control by <br />providing space to store snowmelt floods. <br />Although Flaming Gorge and Glen Canyon <br />ReserVOirs ha'i8 no specifically assigned <br />requirement for flood control, they do reduce <br />flood flows since they are operated to reduce <br />spills. The space they provide Is counted 8S <br />part of the flood control space that Is required <br />by the Army Corps of Engineers (Corps) flood <br />control regulations at lake Mead. <br /> <br />In 1983, Navalo Reservoir reduced the <br />maximum flow of the San-Juan.Rlver at the <br />dam from 8,380 cfs to 2,810 cfs. This reduced <br />damage along the San Juan River, especially <br />near Farmington, New Mexico. The <br />maximum flow of the Gunnison River at <br />Crystal Dam was decreased from more than <br />13,000 cIs to 1 0,000 cfs due to storage In Blue <br />Mesa and Taylor Park Reservoirs. ThIs <br />reduced damage along the Gunnison River, <br />especially near Delta and Grand Junction, <br />Colorado. <br /> <br />Lake Mead Is the only reservoir on the <br />Colorado River In which a specific space Is <br />exclusively allocated for malnstem flood <br />control. Flood control regulations for Hoover <br />Dam have been updated and revised based on <br />findings of alolnt stUdy by Raclamatlon and <br />the Corps. with consultation and advice of <br />State and local Interests. <br />