Wayne N. Aspinall Unit: Briefing on Reservoir Operations

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Introduction The Wayne N. Aspinall Unit (Unit) is located on the Gunnison River in western Colorado. Authorized by the Colorado River Storage Project Act of 1956, the Unit, along with Glen Canyon, Flaming Gorge, and Navajo, provides about 30 million acre -feet of water storage in the Upper Colorado River Basin. As different values for river management compete with traditional uses of water, significant issues of concern to public and natural resource interests need to be addressed. Background The Unit is located in Gunnison and Montrose Counties, Colorado, along a 40 -mile reach of the Gunnison River as shown on page 2. It consists of a series of three dams and reservoirs —Blue Mesa, Morrow Point, and Crystal. The Unit is operated by the Bureau of Reclamation, while the land and water areas of the reservoirs are managed by the National Park Service as the Curecanti National Recreation Area. Reclamation operates the reservoirs and powerplants to meet the following authorized purposes: ♦ regulate the flow of the Colorado River ♦ store water for beneficial consumptive uses ♦ allow the Upper Basin states to use the apportionment made to and among them through the Colorado River Compact and the Upper Colorado River Basin Compact ♦ provide for the reclamation of and and semiarid land ♦ provide for flood control ♦ provide for fish and wildlife enhancement and public recreation ♦ generate hydropower Primary water storage occurs in the uppermost and largest reservoir, Blue Mesa. Powerplants at Blue Mesa and Morrow Point are generally operated to provide peaking power, while the dam and powerplant at Crystal are operated to even out downstream flows. Blue Mesa Reservoir under a 1957 water storage right has a capacity of 940,700 acre -feet, while the capacity of Morrow Point and Crystal Reservoirs are 117,190 acre -feet and 25,240 acre -feet, respectively. Water can be released from the reservoirs through the powerplants and /or river bypass outlets. Spillway use is limited to periods when the reservoirs are full and high inflows are occurring. The table on page 3 presents information on the reservoirs and outlet /spillway capacities. Just downstream from Crystal Dam is the Gunnison Tunnel, an historic diversion for the Federal Uncompahgre Project serving Montrose and Delta Counties. Irrigation diversions up to 1,135 cubic feet per second (cfs) flow are made under a 1905 water right through the tunnel during the irrigation season. Immediately downstream from the tunnel, the Black Canyon of the Gunnison National Park (National Park) stretches 14 miles along the Gunnison River. The Gunnison Gorge includes the next 16 miles of the river below the National Park and is managed by the Bureau of Land Management. The Colorado Water Court has awarded the United States a 1933 Federal reserved water right for flow in the Gunnison River for the National Park (formerly National Monument). The