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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As Lake Mead remains near capacity and flood control releases are required by the Hoover Dam
Flood Control Regulations, consideration will be given to making these releases over the fall and
winter months of! 999 to avoid high flow releases during the January through July runoff season
in year 2000. 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, property, and river stabilization.

Lakes Moban and Havasu

At the beginning of water year \999, Lake Mohave was at elevation 196 meters (644,\ feet) with
an active storage of2, 133 MCM (1.729 MAF). The water level of Lake Mohave was regulated
as needed between elevation \94 meters (636 feet) and 196 meters (644 feet) throughout the
water year ending at elevation 194 meters (636 feet) with \,869 MCM (1.5\5 MAF) in storage,
The total release from Lake Mohave through Davis Dam was 13,902 MCM (I 1.270 MAF) for
downstream water use requirements, flood eontrol, and space building.

For water year 2000, Lake Mohave is expected to release 14,031 MCM (11.375 MAF), The
waterlevel will be regulated between elevation \92 meters (630 feet) and 196 meters (643 feet).

Lake Havasu started water year 1999 at elevation 136.3 meters (447.2 feet) with 697 MCM
(0,565 MAF) in storage, During the year, 10,734 MCM (8.702 MAF) was released from Parker
Dam, In addition to these releases, 1,632 MCM (1.323 MAF) was diverted from Lake Havasu
into the Central Arizona Project (CAP) and 1,485 MCM (1.204 MAF) by the Metropolitan Water
District (MWD).

For water year 2000, Lake Havasu is expected to release \ 0,803 MCM (8. 758 MAF). Diversions
from Lake Havasu by MWD and into CAP are expected to be 1,612 MCM (1.307 MAF) and
1,759 MCM (1.426 MAF), respeetively.

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 eorrespond with maintenanee at both Davis
and Parker Powerplants whieh is scheduled for September through February, The normal filling
pattern of these two reservoirs coincides well with the fishery spawning period, Since lake
elevations will be typical of previous years, normal conditions are expected for boating and other
recreational uses.

Reclamation is the lead agency in the Native Fish Work Group, a multi-agency group of scientists
attempting to augment the aging stock of the endangered razorback sueker in Lake Mohave,
Larval suckers are captured by hand in and around spawning areas in late winter and early spring
for rearing at Willow Beach Fish Hatehery below Hoover Dam. The following year, one year old
suckers are placed into predator-free, lake-side baekwaters for rearing through the spring and
summer. When the lake is normally drawn down during the fall, these fish are harvested from
these rearing areas and then released to the lake. The suckers grow very quickly, usually
exceeding ten inches in length by September.

December I, 1999

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