WSP06774

• File Number: 8282.600.10
• Description: Colorado River Annual Operating Plan
• Basin: Colorado Mainstem
• Date: 12/14/1999
• Author: USDOI/BOR
• Title: 29th Annual Report and 2000 Annual Operating Plan for Colorado River System Reservoirs
• Water Supply Pro - Doc Type: Publication

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Blue Mesa, Morrow Point, and Crystal Reservoin (AspinaU Unit)

In water year 1999, the April through July unregulated runoff into Blue Mesa Reservoir was
834 MCM (0.676 MAF), or 97 percent of average. Water year 1999 unregulated inflow was
1,293 MCM (1.048 MAF), or 108 percent of average. Water year 1999 powerplant bypasses
were approximately 232 MCM (0.188 MAF) at Crystal, the result of annual system maintenance
and spring runoff exceeding powerplant capacity. Releases and spills up to 109 cms (3,840 cfs)
oecurred at Crystal with flows in the river below the Gunnison Tunnel in excess of85 ems (2,900
cfs). Blue Mesa nearly filled in water year 1999, reaehing a peak elevation of2291.96 meters
(7,519.21 feet) on July 31,1999.

Section 7 consultation with the Fish and Wildlife Service on the operation of the Aspinall Unit
continued in 1999. A 5 year effort to study the effect of various release patterns on habitat,
reproductive success, and reintroduction of endangered fish in the Gunnison River was completed
in 1998. The Fish and Wildlife Service is expected to issue a draft biological opinion on the
operation of the Aspinall Unit in 2000. Additionally, negotiations between Reclamation, the
National Park Service, and the State of Colorado to develop a contract to deliver water from the
Aspinall Unit to the Black Canyon of the Gunnison National Monument, in recognition of the
reserved right for the monument, are expected to continue.

For water year 2000 operations, Blue Mesa Reservoir will be drawn down to at least an elevation
of 2,283 meters (7490 feet) by December 31, 1999, in order to minimize icing problems in the
Gunnison River. Blue Mesa will continue to be drawn down through April 2000 to a level that
will accommodate the current most probable inflow scenario and aeeomplish the release
objectives with minimal powerplant bypasses at Crystal.

The minimum release objectives of the Aspinall Unit are to meet the delivery requirements of the
Uneompahgre Valley Project, to keep a minimum of8.5 ems (300 cfs) flowing through the Black
Canyon of the Gunnison National Monument, and to maintain a minimum of8.5 ems (300 cfs)
below the diversion structure at Redlands (at the confluence of the Gunnison and Colorado
Rivers) during the summer months. Under all three inflow scenarios, Blue Mesa is expected to
fill in the summer of 2000 and flows through the Black Canyon of the Gunnison National
Monument are expected to be above the minimum release objective during the summer months.
Filling of the reservoir in water year 2000 will ensure that reasonable specific releases required
to study the protection and improvement of habitat for endangered fish can be accommodated.
The forecasted runofffor the spring of2000 will be closely monitored to achieve these objectives,
To protect both the blue ribbon trout fishery in the Blaek Canyon and recreation potential,
releases during 2000 will be planned to minimize large fluctuations in the daily and monthly flows
in the Gunnison River below the Gunnison Tunnel diversion.

Navajo Reservoir

The San Juan River basin experienced a very dry winter, and in early April, inflow forecasts were
calling for April through July inflow to be only 49 percent of average, April and May, however,
turned out to be months with abundant precipitation in the San JUlin Basin. April through July

December I, 1999

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