WSP11243

• File Number: 8449.900
• Description: Bear Creek
• State: CO
• Basin: South Platte
• Date: 6/1/1983
• Author: Resource Consultants
• Title: Legal and Physcial Water Availability Bear Creek Lake
• Water Supply Pro - Doc Type: Publication

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The monthly water availability obtained at this point is at the

Sheridan gage rather than at Bear Creek Lake which is approximately 6.3

miles upstream from the gage. The Sheridan gage record reflects all

historic diversions above the gage and also includes some return flow,

primarily from irrigation, that enters Bear Creek on that 6.3-mile reach

below the reservoir dam to the Sheridan gage. Rather than attempting a

complex and speculative analysis of the return flows of this reach alone,

quantities developed in the "Preliminary Reservoir Regulation Manual" were

used in this study.

The U.S. Army Corps of Engineeers has investigated river gains and

depletions that take place between the river gages at Morrison and Sheridan

on Bear Creek. The average monthly gain or loss figures based on the flow

records of the 1928-1974 period displayed in Table 4 of the above mentioned

manual show return flows over the December 1 through May 31 period,

depletions over the June 1 through October 31, and neither gain nor loss

through the month of November.

For the purposes of this study it was assumed that all return flows

reach Bear Creek below Bear Creek Lake dam and, therefore, are unavailable

for storage in the reservoir. On this ground, the available water volumes

developed for the Sheridan gage location of the creek were reduced from

December through the following May by the corresponding average return flow

amount in order to obtain the monthly volumes available for storage in the

reservoir (shown in Table 1).

A sequential plot of the same data is included in Fig. 1. The "Avail-

able Monthly Runoff" is shown up to 11,000 acre-feet per month. In 10

months this limit was exceeded, in which case the plot only showed runoff

up to 11,000 acre feet--the exact quantity can be obtained from Table 1.

Results, Interpretations

Rather than examining the table of numeric quantities of the available

runoff, more information is provided by Fig. 1.

The somewhat uniform 1-to-2-month high peaks indicate that significant

benefits could be gained if the allowable storage volume were of the range

of 8,000-12,000 acre-feet rather than if kept below 5,000 acre' feet.

RESOURCE: CON<;ULTf\NT<; INC

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