WSP12637

• File Number: 8282.300
• Description: Colorado River Operations and Accounting - Lower Basin Administrative Procedures
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/1/1996
• Author: DOI-BOR
• Title: Description and Assessment of Operations-Maintenance and Sensitive Species of the Lower Colorado River - Volume I - Report - 08-01-96
• Water Supply Pro - Doc Type: Report/Study

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facility. Water schedulers collect data from CAP, MWD, and others who divert from this
reach of the river. These data are added to the Parker Dam facility's total scheduled plant
water releases, and while considering flood control reservoir elevation on Lake Havasu, the
total daily water releases are calculated for Davis Dam. The flood control reservoir
elevation requirements for Lake Havasu are shown in Figure 15. The hourly release profile
is determined by electric service customer requirements, the current downstream river needs,
and upstream Lake Mohave requirements. Between 2 p.m. and 3 p.m. the current day's
schedule is revised and the next day's schedule is set by schedulers to meet the daily required
downstream water releases and incorporate any daily changes. The control room operator,
located at Hoover Dam, normally fine tunes the hourly release flows between the hours of
8 p.m. and 12 midnight daily to stay within plus or minus 300 cfs of the total scheduled
downstream requirement.

c. Davis Dam to Hoover Dam

The third reach starts at Davis Dam and goes upstream to Hoover Dam. Reclamation
combines the total estimated daily water release requirement of Davis Dam and the target
Lake Mohave elevation to determine monthly the amount of water required downstream of
Hoover Dam. This monthly release is formulated into a monthly energy figure. The
monthly energy figure! is sent to W APA and the estimated daily energy schedule is set by its
power scheduling personnel. The Hoover Dam generators are set on Automatic Generation
Control (AGC) which follows the power system's actual dynamic demands (See Figure 16,
Typical Dynamic Power Generation). This graph represents the dynamic energy changes for
each hour. The actual downstream water flow releases follow these patterns exactly. These
monthly water and power figures are monitored by the scheduler. If the Lake Mohave
elevation approaches the set highllow constraints, the scheduler coordinates with W APA's
power scheduler in setting a new energy target if necessary (See Figure 17, Lake Mohave
Operational Constraints graph).

The Lake Mohave operational constraints are not to drop the lake's elevation more than
2 feet in any lO-day period between February and April. During this time period, energy is
targeted for a lO-day period. The lake's elevation is not allowed to drop below 640 feet msl
between April and the end of July and remains above elevation 637 feet msl until after
September 16th. These voluntary constraints (represented by curve A in Figure 17) are for a
5-year period ending in 1998 and are to accommodate the Razorback Sucker Program. After
this 5-year period, the future operations of Lake Mohave will revert to the pattern shown on
curve B in Figure 17.

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