8031

• UCREFRP Catalog Number: 8031
• Author: U.S. Department of the Interior.
• Title: Fish and Wildlife Service Final Biological and Conference Opinion on Lower Colorado River Operations and Maintenance - Lake Mead to Southerly International Boundary.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

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BIOLOGICAL OPINION

Proposed Action

range in elevation was from 210 feet to 251 feet msl (the top of the spillway). Several potential
repairs for Senator Wash that could allow full utilization of its storage capacity are under current
review, but it will be a number of years before repairs can be accomplished. The reservoir
elevation is continually fluctuating because Senator Wash is used to regulate flows arriving at
Imperial Dam.

3. Water Deliveries to Mexico

Mexico is entitled to receive a total of 1.5 maf of water delivered at the NIB and SIB each year _
of which at least 1.36 maf are to be delivered via the Colorado River (normally consisting of
releases from Colorado River system storage and drainage returns) to the NIB. Up to 140,000
acre-feet of Colorado River water (normally consisting of drainage returns and wasteway flows)
can be delivered at the sm. In the event of a declared shortage, water deliveries to Mexico woul d
be reduced in the same proportion as consumptive uses in the United States are reduced.

In December of each year, Mexico provides the United States with an advance monthly water orde r
for the following year. This water order can only be changed by providing the United States 30
days' advance notice, and each monthly water order can be increased or decreased by no more than
20 percent of the original monthly water order. The treaty further stipulates that Mexico's total
water order must be no less than 900 cfs and no more than 5,500 cfs during the months of January,
February, October, November, and December. During the remainder of the year, Mexico's water
order must be no less than 1,500 cfs and no more than 5,500 cfs. Daily water orders are usually
not allowed to increase or decrease by more than 500 cfs.

4. Power Operations

Each of the major LCR hydroelectric facilities have legislati ve authorization for the production of
electric power. Reclamation is the Federal agency authorized to produce this power. Water is
released from Hoover Dam (approximate elevation 1,200 msl) through a combination of 19
dedicated generator pipes into Lake Mohave (approximately 640 feet in elevation). Water is then
released through Davis Dam through a combination of five dedicated generator pipes into
Lake Havasu (approximate elevation 448 feet). Since Parker Dam is the last major United
States-owned, Reclamation-administered, hydroelectric facility on the LCR and there is no other
significant downstream storage, all releases scheduled from Parker Dam are in response to
downstream water orders or reservoir regulation requirements.

Although Reclamation is the Federal agency authorized to produce this power, Western Area
Power Administration (W AP A) is the Federal agency authorized to market this power. W AP A
enters into electric service contracts on behalf of the United States with private and municipal
entities. Reclamation is obligated to meet the Hoover, Parker, and Davis Dams' power generation
schedules which are produced by W APA in accordance with existing electric service contracts,

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