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In water year 1991, Lake Mead storage decreased by 911 ,000 acre- feet since the minimum release objective of8,230,000 acre-feet was released from Lake PoweIl and water delivered out ofLake Mead totalled 9,227,000 acre-feet. In water year 1991, most of the reservoirs upstream of Lake Powell fiIled and are currently being drawn down in anticipation of a near-normal runoff in 1992; however, the lingering dry basin conditions are expected to affect the quantity of runoff into Lake Powell in 1992. a. Lake Powell Lake Powell reached its high content ofl5,887,900 acre-feet on June 30,1991, and its low content ofl4,533,200 acre-feet on April 12, 1991. At Lees Ferry, the calculated discharge for the water year ending September 30, 1991 was 8,111,000 acre-feet, including approximately 10,000 acre-feet from the Paria River. Lake Powell finished the 1991 water year with a measured annual release of 8.23 maf all of which went through the power plant except 17,000 acre-feet. On July 31,1991, the test flows for the Glen Canyon Environmental Studies (GCES) were completed on schedule. On August 1, 1991, the Secretary of the Interior announced that test interim flows controlling minimum, maximum and fluctuating releases would be implemented at Glen Canyon. These test interim flows were developed using the best available information and were implemented at that time in order to test the feasibility of limiting releases on an interim basis until the completion of the GeEIS. After a favorable completion of the test interim flows and the completion of exception criteria, interim flows were implemented at Glen Canyon Dam on November 1, 1991. The interim flows will remain in effect until completion of the GCEIS in order to reduce the alleged effects of power operations on downstream natural resources. In 1992, the most probable April through July runoff into Lake Powell is expected to be 5,700,000 acre-feet or approximately 70 percent of the long term average. The most probable maximum content of Lake Powell is expected to be approximately 15.9. Considering the current amount of storage and the level of expected runoff, the risk of spilling is negligible. 58