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Introduction Concrete torms on the Havasu Pumping Plant The operation of tne Colorado River Basin during the past year and the projecled operations for the current year reflect domestic use, irrigation, hydroelectric power generation, flood control, water quality control. fish and wildlife propagation, recreation, and Colorado River Compact requirements. Storage and release of water from the Upper Basin reservoirs are governed by all applicable laws and agreements concerning the COlorado River, including the impoundment and release of water in the Upper Basin required by See, 602(a) of Public Law 90-537, The operation of the Lower Basin reservoirs reflects Mexican Treaty obligations and Lower Basin contractual commitments. Nothing in this report is intended to interpret the provisions of the Colorado River Compact (45 Stal. 1057). the Upper Colorado River Basin Compact (63 Stal. 31). the Water Treaty of 1944 with the United Mexican States (Treaty Senes 994, 59 Stal. 1219). the decree entered by the Supreme Court of the United Slates in Arizona v, California. el al. (376 U,S, 340), the Boulder Canyon Project Act (45 Sial. 1057). the Boulder Canyon Project Adjustment Act (54 Stal. 774; 43 U,S,C, 618a), the Colorado River Storage Project Act (70 Stal. 105: 43 U,S,c, 620), or the Colorado River Basin Project Act (82 Stal. 885; 43 USC, 1501), 2 . Authority for Report Actual Operations Under Criteria - Water Year 1981 Rail race on the Green Alver. Pursuant to the ColoradO River Basin Project Act (Public Law 90-537) of 1968. I am pleased to present to the Congress, and to the Governors of the Colorado River Basin States, the eleventh annual report on the Operation 01 the Colorado River Basin, This report describes the actual operation of the reservoirs in the Colorado River drainage area constructed under the authority of the Colorado River Storage Project Act, the Boulder Canyon Project Act. and the Boutder Canyon Project Adjustment Act durlng.water year 1981 and Ihe projected operation of these reservoirs during w?t~r year 1982 under .Jhe ~Criteria for Coordinated Long-Range Operation of Colorado River Reservoirs," published in the Federal Register June 10, 1970, James G, Watt. Secretary U,S, Department of the Interior The Initial operational plan for water year 1981, assuming average runof1 conditions, reflected the concepts of equalization of storage between Lake Powell and Lake Mead and anticipatory releases tram Lake Mead for flood control and river regulation purposes. However, beginning in November 1980, precipitation at the 13 selected stations dropped below normal and continued this decline throughout the year. In view of the' January forecast of below normal April-July runof1 and projected reservoir conditions, the operating plan was modi1ied to provide for minimum releases from Lake Powell and reduced releases from Hoover to meet downstream requirements. During water year 1981 , the water supply in the Colorado River Basin was approximately 49 percent of the long-term average, ranging from 58 percent for the Green River above Flaming Gorge Dam to 49 percent for the San Juan River above Navajo Dam The major storage reservoirs in the Colorado River Basin stayed within the normal operating range during water year 1981, Aggregate Colorado River system storage at the end ot the water year was 49.573.000 acre-feet, representing a decrease of 4,941 ,000 acre-feet from the previous year. Despite the extremely low runoff, active storage in the system was approximately 88 percent of the January 1 maximum available storage, due to the large carryover from previOUS years.