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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The daily and hourly water release target process is set by collecting data in the reaches
between Hoover, Davis, and Parker Powerplants as well as the SIB. The availability of
water is determined by. the 24-month study which is updated on a monthly basis. The
24-month study is compiled from present snow pack water content, reservoir storage,
projections from water' users for the current year and projections from historical data
forecasting. The availability of generating units to deliver the required downstream flows is
coordinated with the p~ojected 24-month study and the 18-month unit outage estimate. The
18-month estimated individual unit maintenance schedule incorporates monthly water delivery
needs, the contractual requirement of WAPA's electric service customers, and required
generator maintenance work. The annual 18-month unit outage schedule is updated on a
monthly basis if changes are required.

a'. Parker Dam to Mexico

The first reach from the SIB extends up river to Parker Dam, located at Parker, California,
and is under the jurisdiction of Y AO. Y AO collects data from Mexico, the All-American
Canal users, the Gila Gravity Main Canal users, North Gila Canal, various Indian Tribes,
PVID reservoirs, etc. ,These data are combined and sent to the water scheduling office
located at the Hoover Dam facility. The lower Colorado River dam's schedulers profile
hourly releases using ~e electric service customer's energy load profiles. Water from
Parker Dam has a 3-d~y travel time to Imperial Dam, a major diversion point for irrigation.
Elevated water releases on Saturday and Sunday, when power is in less demand and revenue
is less, will arrive at Imperial Dam on Tuesday and Wednesday, workdays for the growers.
Conversely, low relea~es on Wednesday and Thursday (when power has a higher "weekday"
value) will arrive at Imperial Dam on Saturday and Sunday, not typically workdays for the
growers. These profiles are coordinated with WAPA's power schedulers in Phoenix,
Arizona, and the control room operators located at Hoover Dam. The "Parker Schedule
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Today," Figure 14a, is an example of the hourly projected release schedule. Between 2 p.m.
and 3 p.m. the current day's schedule is revised and the next day's schedule is set by Hoover
water operations schedulers to meet the daily required downstream water release and to
incorporate any changes. The control room operator normally fine tunes the hourly release
flows (see hand-marked changes) between the hours of 8 p.m. and 12 midnight daily to stay
within plus or minus ~O cfs of the total scheduled downstream requirement. The "Parker
Actual Release," Figure 14b, shows actual historical hourly release data for the Parker Dam
facility. The Parker g~nerating units are not normally placed on dynamic control (dynamic
control causes the unit~ to fluctuate on a 4-second interval), which would subject them to
unscheduled river flo\\{ changes, which minimizes hourly downstream fluctuations. The
hourly flow changes b~gin at 10 minutes to the hour and are fully implemented 10 minutes
after the hour. These iflow changes are computer controlled, and varying rates of unit
releases over time can be changed.

b. Parker Dam to Davis Dam

The second reach starts at the Parker Dam facility and goes upstream to the Davis Dam

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