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

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

o Q 2 3 ~:f
i
i
,

Prior to the beginning! of the calendar year, diversion schedules are requested from water
users entitled to Colod1do River water. These schedules are of estimated monthly diversions,
which allows Reclamation to determine a tentative schedule of monthly releases through the
I .
Hoover Powerplant. tctual monthly releases are determmed by the demand for water
downstream of Hoover Dam. Daily changes in water orders are made to accommodate
emergencies, rainstorJs, changes in wind, holidays, and various other parameters.
Appendix E provides additional information on reservoir releases and elevations for
non-flood release year$ during 1980-1995 and projected releases from 1996-2010.

i
3. Operation of the Colorado River Below Davis and Parker Dams
I
I

The scheduling and subsequent release of water through Davis and Parker Dams effect daily
fluctuations (going thrbugh its changes in a day, a day being 24 hours) in river flows,
depths, and water surf~ce elevations downstream of these structures. Since such releases
may affect downstream critical habitat reaches, typical seasonal flow patterns are illustrated
for representative gauging locations on the lower Colorado River (Figures 9-13). The
location of the represerttative gauging stations are shown on Figure 2 and their names and
I
distance (in miles) from the SIB are: Davis Dam, 275.4; Parker Dam, 192.2; Water Wheel,
152; Taylor Ferry, 1O~.6; and below Cibola Valley, 87.3. Typical seasonal flows (in cfs)
and water surface elev~tions (in feet msl) are shown for each of the five stations. Variations
in water depths are illustrated for representative stations in Appendix E.
I

Figures 9 and 10 demdnstrate that the water surface elevation fluctuates most noticeably in
the river reaches c1ose$t to the dams. Those fluctuations become more and more attenuated
I
as the distance downst~eam increases, as shown in Figures 12 and 13. The Mohave Valley
and Parker Divisions ~f the river are most affected by fluctuations on a daily basis. The
Imperial, Laguna and yuma Divisions are the least affected. The river fluctuates seasonally
with the highest water levels occurring during the summer and the lowest water levels
occurring during the l~te fall and winter, except during flood releases. The current
ecosystem on the river lis, in part, a result of these daily and seasonal fluctuations.

,
Under normal operatin~ conditions, Reclamation's Yuma Area Office (YAO) receives daily
water orders for those ~ater entitlement holders within the United States and Mexico below
Parker Dam. Water oiders are totaled and submitted to Hoover Dam personnel who then
coordinate releases to ~eet downstream water demand and power demands from Parker,
Davis, and Hoover Dains.

Mexico submits each Wednesday a daily water order, to cover the following week, through
IBWC at Yuma; howe~er, Mexico cannot change its daily water order once it is received,
except in the case of all emergency. United States water entitlement holders below
Parker Dam also furnish their water orders to Y AO each Wednesday; however, United States
water entitlement holders may modify their master schedule of water orders at least 3 days in
advance of water relea~s from Parker Dam, and they may also vary from their master
schedule on a daily basts if necessary. Release requirements from Parker Dam are equal to

42