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Plan of Operation- Water Year 1978 For average runoff conditions during water year 1978, the projected operation of each of the reser. voirs in the Colorado River Basin is described in the following paragraphs. Charts 1 through 10 show hydrographs of the projected monthly out1\ow from the reservoirs and the projected end.of.month ele. vation and active storage in the reservoirs for average and three other assumptions of 1978 modified runoff from the Basin. The four assump. tions are: (I) AVERAGE based on the 1906.68 rec. ord of runoff, (2) UPPER QUARTilE based on the level of annual streamflow which has been ex- ceeded 25 percent of the time during 1906-68, (3) LOWER QUARTilE based on flows exceeded 75 percent of the time during 1906-68, and (4) MOST ADVERSE based on the lowest year of record, which occurred in 1977. Because of the record low inflow during water year 1977, the water year 1978 projected releases from Lake Powell are 8.23 million acre-feet for all four assumed runoff conditions. The projected operations of lake Mead, lake Mo. have, and Lake Havasu are the same under all four of the runoff assumptions. ALTERNATIVE PLAN OF OPERATION A review is currently being made of the terms and conditions of the merits of alternative plans of op- eration associated with the release of water from Lake Mead in excess of downstream requirements for beneficial consumptive use. Also included is the joint study by the Bureau of Reclamation and the Corps of Engineers to determine the best flood con- trol operation for lake Mead and Hoover Dam. Because of the extreme drought conditions during 1976 and 1977, no releases in excess of down- stream requirements are anticipated during water year 1978. However, such additional releases are recognized as a possibility before 1985, when the Central Arizona Project is scheduled to begin di- versions. Snowmobile races, Blue Mesa Reservoir, Colorado. 32