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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In January 1992, the Denver Regional Council of Governments (DRCOG)
requested the 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 would make variable
releases through the year depending on the inflow. The following table shows the
approximate release targets as requested by DRCOG:

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STREAMFLOW

RELEASE

> 20 efs
15 - 20 efs
10 - 15 efs
< 10 cfs

10 cfs
7 - 9 cfs
5 - 6 efs
o cfs

Release changes were made weekly as needed throughout the year and will continue
through December 1992.

(b) Chatfield Reservoir, Colorado. During the reporting period, a total of
6 release orders were made while the pool was in the flood control zone. The releases
ranged from 400 cfs to 100 cfs and were required only to release inflows to maintain the
target pool elevation of 5432.0. These releases occurred between March 5, 1992 and April
21,1992. Before and after these dates, releases were made by the State Engineer. Gated
releases made by the State Engineer varied from a maximum of 550 cfs on August 6,1991,
to 0 cfs on September 11-15,26-30, and October 1-31. A total of 19,105 AF was delivered
via the canals during the reporting period compared with 14,940 AF during the last
reporting period. The pool was in the flood control storage zone only slightly from March
1-10, March 25 - April 1, and April 7-21. The maximum pool elevation during this period
was 5432.48 on April 19,1992. All other release orders during the reporting period were
made by the State Engineer or his representative.

(e) Cherry Creek Reservoir, Colorado. On April 1, 1988, the State of
Colorado, through the State Engineer, implemented strict administration of water rights
within the Cherry Creek Basin. When a senior river call is in effect, Cherry Creek
Reservoir is required to pass inflow through the project. Releases from the project were
coordinated by the Water Control Section to comply with downstream river calIs as
deteffilined by the Colorado State Engineers Office. A total of 14 release orders were made
during the report period. The releases were made to meet downstream water needs and for
a sediment flushing exercise. Releases varied from 50 cfs to 2 for water control and water

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