WSP07886

• File Number: 8282.600.10
• Description: Colorado River Operating Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1994
• Author: USDOI/BOR
• Title: Operation of the Colorado River Basin 1994 Projected Operations 1995
• Water Supply Pro - Doc Type: Publication

Reservoir Operations

Daily releases are provided from the storage reservoirs in
the Lower Basin to meet the needs of water user agencies,
for river regulations, and as needed for flood control. When
possible, all waler passes through the powerplant units. The
daily releases are regulated on an hourly basis to balance the
power needs of the hydroelectric power customers, the flow
needs of endangered species of fISh (Upper Basin only) and
recreational needs. In general, controUed releases allow for
an extended recreation season, and reduce the high flow
periods in May and June.

The runoff into Lake PoweU for water year 1994 was below
average. Unregulated inflow into Lake PoweU was 57 percent
of average for water year 1994, Of the unregulated inflows
for water years 1988 through 1994, six of seven years were
below average, only 1993 was above average. Storage in
both Lakes PoweU and Mead, decreased in waler year 1994.
Lake PoweU decreased by 1,298 million cubic meters
(1,052,000 acre-feet) in water year 1994, while Lake Mead
decreased by 1,787 million cubic meters (1,449,000 acre-feet).

Operational objectives at and below Laguna Dam are to re-
regulate releases from Imperial Reservoir to conserve water,
control sediment, and maintain the river channel. Storage
above Laguna Dam in the reservoir, in surcharge, and in
bank storage provides for controUed flows in the river at
Yuma and the Northerly International Boundary.

When combined with downstream drainage, Laguna releases
provide a continuous live stream for recreation and fish and
wildlife. On a few occasions each year, higher releases from
Laguna Reservoir, caused by rainstorms or user rejected
water orders, are used to maintain river channel capacity.
This occasional practice reduces channel maintenance
expense without impairment to water conservation or power
production.

Based on existing reservoir conditions and river regulation
operations below Hoover Dam, the totrJ 1995 delivery to
Mexico is scheduled to be a treaty delivery of 1,850 million
cubic meters (1,500,000 acre-feet) for the calendar year. In
addition, approximately 173 million cubic meters (140,000
acre-feet) of drainage waters are expected to bypass to the
Gulf of California via the Bypass Drain during calendar year
1995. This bypass channel was constructed pursuant to
provisions of Minute No. 242 of the International Boundary
and Water Commission.

Based on existing conditions it is anticipated that the Gila
River will have no adverse impacts to Colorado River
operations for water year 1995.

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