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Projected Plan of Operation. Water Year 1989 A proposed operation plan for water year 1989 for major reservoirs of the Colorado River system was formulated and distributed to representatives of the Colorado River Basin States in November 1988. This plan was prepared in accordance with the Operating Criteria published June 4, 1970, in compliance with Section 602, Public Law 90,537. The plan reflects operation for flood contro~ domestic and irrigation use of water, hydroelectric power generation, water quality contro~ fish and wildlife propagation, recreation, and Colorado River Compact requirements. During the first two months of water year 1989, releases will be at 28 percent of powerplant capacity at Glen Canyon, then releases will increase to 40 percent during December 1988. Releases from January through July will be based upon the runoff forecasts received during that time but will result in greater available space on August I, 1989, than the minimum flood control requirement of 1.5 MAP. The plan calls for a total Glen Canyon release in water year 1989 of 8.23 MAF under reasonable minimum inflow conditions. An annual release of8.45 MAF would be required under most probable inflow conditions, which would fill Lake Powell to 95 percent full at the end of the runoff season and also equalize the active contents of Lake Powell and Lake Mead to within 500,000 acre-feet of each other by September 30, 1989. With a reasonable maximum inflow during water year 1989, the projected Glen Canyon releases would be 14.1 MAF. This volume of inflow would require 81 percent of maximum powerplant releases during April through June, 70 percent during July and August, and 55 percent during the remainder of the water year. The projected operation for most probable runoff conditions for the major reservoirs in the Colorado River Basin for water year 1989 is described in the following pages. Charts showing the projected monthly outflows from each reservoir for the three assumed hydrologic conditions are presented with each reservoir operation. Each of these assumptions uses the most current hydrologic information available by including actual forecasted October through December 1988 inflows. The monthly inflows for the remainder of the year were based upon the following assumptions: (1) reasonable maximum based upon the annual volume of \nflow which would be exceeded about 10 percent of the time. (2) most probable based upon the annual 1906 through 1985 natural flows developed for the Colorado River Simulation System (CRSS) model depleted up to current levels; and (3) reasonable minimum based upon the annual volume of inflow which would be exceeded about 90 percent of the time. 4