WSP01172

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1997
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

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Lake Mead

With the increased releases out of Lake Powell during the late summer and fall of calendar
year 1996, Lake Mead finished out the year with 26,663 MCM (21.616 MAP) in storage at
elevation 362.9 meters (1190.86 feet), which is 83 percent of conservation capacity. Full
conservation pool at 371.9 meters (1219.6 feet) has a capacity of31,919 MCM
(25.877 MAP).

The surplus condition is the criterion governing the operation of Lake Mead for calendar year
1997 in accordance with Article ill(3)(b) of the Operating Criteria and Article II(B)(2) of the .
decree in Arizona v. Califoinia. The outlook for lowest and highest monthly releases under
the most probable inflow conditions for calendar year 1997 will be 480 MCM (.389 MAP)
and 1,396 MCM (1.l32 MAP) respectively.

Lake Mead water surfuce elevation is expected to rise to 365.4 meters (I 198.8 feet) in
February 1997, with 28,057 MCM (22.746 MAP) in storage, which is 88 percent of
conseIVation capacity. Storage is projected to decline to elevation 362.8 meters (1190.2 feet)
by June 1997, or 83 percent of conservation capacity with 26,560 MCM (21.533 MAP) in
storage. By the end of calendar year 1997, Lake Mead storage is projected to be at elevation
363.3 meters (1192 feet) with 26,887 MCM (21.798 MAP) in storage, which is 84 percent of
conservation capacity. No flood control releases above doWnstream water d~mands would
be anticipated in 1997 under the most probable and minimum probable inflow conditions.
Flood control releases above downstream water demands would be anticipated under
maximum probable inflow conditions in 1997 for all months except August, with peak
releases of about 764 ems (27,000 cfs) occurring in October.

Drawdown during the peak largemouth bass spawning period in April and May is planned to
be near the limits of decline recommended in the July 1982 final report of a five-year study
by the Arizona Game and Fish Department and the Nevada Department ofWtldlife. In
future years, as Lake Mead refills and flood control releases are again required by the Hoover
Darn Flood Control Regulations, consideration will be given to making these releases over
the fall and winter months to avoid high flow releases during the January through July runoff
season. This distribution of water reduces the chance of bypassing hydroelectric powerplants
below Hoover Dam and avoids the adverse impacts of higher flood control releases on fish
and wildlife, recreation, water quality, and river stabi1ization.

Lakes Mohave and Havasu

Mohave and Havasu Reservoirs are scheduled to be drawn down in the late summer and
winter months to provide storage space for local storm runoff and will be filled in the spring
to meet higher summer water needs. This drawdown will also correspond with maintenance
at both Davis and Parker Powerplants which is scheduled for September through February.
The normal filling pattern of these two reservoirs coincides well with the fishe~ spawning

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