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I I I I I I I I I I I I I I I I I I I potential, releases during 1999 will be planned to minimize large fluctuations in the daily and monthly flows in the Gunnison River below the Uncompahgre Tunnel Diversion. Navajo Reservoir The April through July unregulated inflow into Navajo Reservoir in water year 1998 was 639 MCM (0.518 MAF) or 76 percent of average. Water year 1998 regulated inflow was 1,046 MCM (0.848 MAF) or 85 percent of average. Navajo Reservoir did not fill in 1998. Section 7 consultation with the Fish and Wildlife Service on the operation of Navajo Dam continued in 1998. Water year 1997 was the seventh year of a seven-year study to evaluate alternative operations of Navajo Reservoir to benefit endangered fish, and a biological opinion on the operation of Navajo Dam is expected in 1999. During the spring large releases of up to 142 cms (5,000 cfs) were made during May and June to coincide with the peak flows of the Animas River. This resulted in peak flows of223 cms (7,885 cfs) at Bluff, Utah. After the completion of the large spring releases, releases were gradually reduced to approximately 17 crns (600 cfs) for the remainder of the year. In water year 1999, Navajo Reservoir is expected to nearly fill under the probable maximum inflow scenario. The reservoir should fill above 8~0 percent of full under the moslProbable and probable minimum scenarios. Releases from the reservoir will be held near 17 cms (600 cfs) through the fall and winter months and large releases will likely be made in May and June in order to improve the habitat and provide better spawning conditions for endangered fish in the San Juan River. Lake Powell The April through July unregulated inflow into Lake Powell in water year 1998 was 10,639 MCM (8.625 MAF) or 112 percent of average. Water year 1998 unregulated inflow was 16,850 MCM (13.660 MAF) or 116 percent of average. Lake Powell ended the water year 12 feet from full. During water year 1999, releases greater than the minimum release objective of 10,152 MCM (8.230 MAF) likely will be made to avoid anticipated spills and/or to equalize the storage between Lakes Powell and Mead;1Jnderthe most probable inflow conditions, releases of 13,322 MCM (10.800 MAF) would be made, while under the maximum probable inflow scenario, approximately 21 ,340 MCM (17.300 MAF) will be released. This maximum probable inflow would require releases of about 708 cms (25,000 cfs) for a lengthy period of time. With current full reservoir system conditions, releases above powerplant capacity arelJossible in 1999. Such releases would be made consistent with the 1956 Colorado River Storage Project Act, the 1968 Colorado River Basin Project Act, the 1992 Grand Canyon Protection Act, and the Secretary Of~ the Interior's agreement for managing spills from Glen Canyon Dam contained in the 1996, 1997, and 1998 AOP's. This agreement provides for the use of reservoir releases in excess of power plant capacity required for dam safety purposes during high reservoir conditions to 10 o~ ."",*/ ,," . ~ (v-( '~9~~o..';b \;;;f/