WSP04310

• File Number: 8449.600
• Description: Chatfield Reservoir
• State: CO
• Basin: South Platte
• Date: 1/1/1984
• Author: CWCB
• Title: Division of Parks Temporary Storage in Chatfield - Background Data
• Water Supply Pro - Doc Type: Data

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BEAR CREEK DAM AND LAKE
BEAR CREEK. SOUTII PLATTE RIVER BASIN, COLORADO
1991-1992 REGULATION

The Omaha District entered into two temporary one year storage contracts for municipal
and industrial water supply under Section 6 of the Flood Control Act of 1944 (Public Law
34, 78th Congress), pending development of a long-term contract under the Water Supply
Act of 1958 as amended (43 U.S.C. 390 b-f). The fIrst contract dated September 17.1987
was for 25 acre feet with the Indian Hills Water District. This contract was renewed in
April 1991. The cost of storage per acre-foot in each of these contracts is approximately
$2700.00.

In response to the contracts for temporary water storage, a revised ,Memorandum of
Understanding (MOU) between the COIpS of Engineers and the State of Colorado was
signed on June 20,1988. This memorandum supersedes the previous MOU dated May 11,
1977. Under normal conditions the Bear Creek Dam outlet works is set to automatically
pass streamflow up to 500 cfs when pool elevations are above the drop inlet-outlet weir crest
of 5558 feet MSL. When conditions warrant, higher releases are made by opening two slide
service gates in the dome type gated control structure buried under the embankment.
Under the revised MOU, the State Engineer or his representative will determine the storage
and releases necessary to satisfy downstream water right requirements w4~n the pool level
is below elevation 5559 ft. MSL. Elevation 5559 is one foot into the flood storage zone and
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was selected to allow flexibility in targeting authorized pool levels. Bear Creek Reservoir
was not made operational during the reporting period as has been done in the past.

The State of Colorado, Department of Natural Resources, Division of Game, Fish and
Parks, in a letter dated October 1, 1970, agreed to provide water for the initial filling and
replenishment of evaporation losses from the recreation pool, by purchase or other means,
consistent with Federal and State laws to assure effective operation of the project for
recreation.

In January 1992, the Denver Regional Council of Govermnents (DRCOG) requested
Corps of Engineers participation in a demonstration project at Bear Creek Reservoir using
hypolimnetic withdrawals throughout the year. The water quality in the reservoir and
downstream of the reservoir would be monitored to assess the effectiveness of this
management practice on water quality. The Corps of Engineers woyld make variable
releases throughout the year depending on the inflow. The table on the following page
shows the approximate release targets as requested by DRCOG.

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