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<br />. .001(7) <br />... <br /> <br />. <br /> <br />. <br /> <br />; , <br /> <br />of approximately 116,000 cfs on June 28, 1983. <br />occurred when the Lake was already full. Lake Powell begun <br /> <br />This <br /> <br />spilling on June 8, with a peak release of 91,000 cfs <br /> <br />occurring on June 29. <br /> <br />The storage in downstream Lake Mead reached the top of <br /> <br />the Hoover Dam spillway gates on July 3, and the first spill <br /> <br />occurred since 1941, when releases were made to test the <br /> <br />dam's spillways. <br /> <br />The nearly doubling of the forecasted <br /> <br />runoff between the May 1 and late June forecasts, with the <br /> <br />reservoirs full, could have required Hoover Dam flood control <br /> <br />releases of up to 65,000 cfs pursuant to the regulations. <br /> <br />However, the Bureau of Reclamation was able to manage the <br /> <br />reservoir system so as to avoid these very damaging releases. <br /> <br />The average monthly release from Hoover Dam was limited to <br /> <br />42,000 cfs. With regard to the frequency of occurrence of <br /> <br />such flows, a 1982 Corps of Engineers report shows a Hoover <br /> <br />Dam release of 40,000 cfs for a one-month duration as a 1 in <br /> <br />200 to a 1 in 333 year event. <br /> <br />Substantially higher than normal releases from Hoover <br /> <br />Dam continued through the remainder of calendar year 1983 and <br /> <br />into 1984 in order to evacuate flood control storage space. <br /> <br />Releases remained above 27,500 cfs during this period. By <br /> <br />comparison, releases from Hoover during the year would <br /> <br />normally range from about 5,000 cfs during low water demand <br /> <br />periods to about 15,000 cfs during high irrigation months. <br /> <br />The 1983 high release rates from Hoover Dam resulted in <br /> <br />flooding of low-lyi~; areas, bank erosion, and the raising of <br /> <br />-8- <br />