BOARD02186

• Board Meeting Date: 1/27/2004
• Description: ISF Section - Instream Flow Appropriations - Dyke Creek
• Board Meetings - Doc Type: Memo

Summary
The information contained in this report and the associated instream flow file folder forms the
basis for staff s instream flow recommendation to be considered by the Board. It is staff's
opinion that the information contained in this report is sufficient to support the fmdings required
in Rule 5.40.

Colorado's Instream Flow Program was created in 1973 when the Colorado State Legislature
recognized "the need to correlate the activities of mankind with some reasonable preservation of
the natural environment" (see 37-92-102 (3) C.R.S.). The statute vests the CWCB with the
exclusive authority to appropriate and acquire instream flow and natural lake level water rights.
In order to encourage other entities to participate in Colorado's Instream Flow Program, the
statute directs the CWCB to request instream flow recommendations from other state and federal
agencies. The United States Forest Service (USFS) recommended this segment of Dyke Creek to
the CWCB for inclusion into the Instream Flow Program. Dyke Creek is being considered for
inclusion into the Instream Flow Program because it has a natural environment that can be
preserved to a reasonable degree with an instream flow water right. The USFS is very interested
in protecting stream flows because Dyke Creek is currently an unregulated stream for much of its
length. Forest Service investigations (unpublished) have suggested that this is a fully functioning
aquatic system that is contributing towards the agency stewardship mission of protecting
sustainable ecosystems. This stream provides occupied habitat for native Colorado River
Cutthroat Trout. Establishment of an instream flow water right would be consistent with the
Conservation Agreement and Strategy For Colorado River Cutthroat Trout. April 2001, which
has a stated goal of "To maintain areas which currently support abundant Colorado River
cutthroat trout and manage other areas for increased abundance".

Dyke Creek is 6.8 miles long. It begins on the Eastem flank of Chalk Mountain at an elevation
of approximately 10,200 feet and terminates at the confluence with West Muddy Creek at an
elevation of approximately 8,600 feet. The entire 5.2-mile segment addressed by this report is
located on federal lands. Dyke Creek is located within Delta County. The total drainage area of
the creek is approximately 4.7 square miles. Dyke Creek generally flows in an easterly direction.

The subject of this report is a segment of Dyke Creek beginning at an Unnamed Lake at 10,225
feet in elevation and extending downstream to the confluence with the Bell Ranch Diversion #1,
elevation 9,000 feet ( see Map). The proposed segment is located 20 miles southeast of the Town
of Collbran. The staff has received only one recommendation for this segment, from the USFS.
The recommendation for this segment is discussed below.

Instream Flow Recommendation(s)

USFS recommended 3.2 cfs, spring and summer; 1.5 cfs late summer and fall; and 1 cfs, winter,
based on its June 18,2003 data collection efforts (see Appendix A). Three cross sections were
surveyed on Dyke Creek. Cross sections #1 and #3 were dropped as a basis for flow
recommendation due to problems with confidence intervals. The problem with #1 is the survey
was conducted during a period the channel was de-watered by the Bell Ranch diversions located
upstream. The problem with #3 are less obvious, but are most likely due to the selection of the
x-section location and its morphology. As a result recommendations are based solely on x-

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