Aspinall EIS - Scoping Report May 2007

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7,490 by December 31 to provide space for the next spring’s runoff and to avoid ice damage upstream . The five generators at the three dams o f the Unit are capable of generating up to 283 megawatts of electricity. Morrow Point is the powerhouse of the Unit — its generators produce twice as much electricity as those at Blue Mesa. The Western Area Power Administration markets electricity generate d by the Unit in conjunction with power from Glen Canyon and Flaming Gorge Dams and other plants of the Colorado River Storage Project as part of an integrated system that provides electricity to all states of the Colorado River Basin . The upstream powerpl ants of the Unit (Blue Mesa and Morrow Point) are critical in that they can be operated to provide peaking power (high flexibility in release rates) . Crystal Reservoir then serves as a regulation reservoir to stabilize flows to the Gunnison River. Pub lic recreation use of Aspinall Unit lands and water are managed by the National Park Service as the Curecanti National Recreation Area. Blue Mesa Reservoir supports around 1,000,000 recreation visitor days per year. Fishing, boating, and camping are prim ary recreation uses. Fishing and rafting are important recreation activities downstream from the Unit. Approximately 3 miles downstream from Crystal Dam, the Black Canyon of the Gunnison National Park begins and stretches 14 miles along the Gunnison Riv er. Downstream from the National Park, lands are administered by the Bureau of Land Management as the Gunnison Gorge National Conservation Area. At the United States Geological Survey gage at the head of the Black Canyon , historical average monthly flow s have been 1,320 cfs and daily flow extremes have ranged from a few days of no flows to 19,000 cfs. Another important measurement point on the river is the Whitewater gage, eight miles upstream from the Colorado River confluence and approximately 90 mile s downstream from Crystal Dam . At this point the drainage area is roughly 8,000 square miles; average monthly flows are approximately 2,600 cfs, and historic extremes have ranged from 106 cfs to over 35,000 cfs. The Aspinall Unit stores water during spri ng runoff and re leases it when needed to meet downstream needs. Unit regulation since 1969 has reduced Gunnison River flows during spring runoff and increased flows during the non - runoff months. Even with regulation, however, flows vary with the amount o f snowfall. For example, annual flows through the Black Canyon averaged 396 cfs during 1977 and 2,943 cfs during 1984. Unit operations provide flood control benefits, both upstream and downstream of the reservoirs. One of the operational sideboards fo r high water years is to reduce flooding through the Delta area during spring runoff. Coordination of the Aspinall Unit and Taylor Park operations reduce upstream flooding. During the winter months, Blue Mesa Reservoir is drawn down approximately 30 fee t from full (7490 feet elevation) to help reduce winter flooding caused by ice jams upstream from the reservoir near the city of Gunnison. 4