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• Board Meeting Date: 11/18/2007
• Description: ISF Section - Uncontested 2007 Instream Flow Appropriations
• 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 findings 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 Bureau of Land Management recommended this segment of Pauline Creek to the
CWCB for an enlarged water right under the Instream Flow Program. Pauline Creek is being
considered for an enlargement because it has a natural environment that can be preserved to a
reasonable degree with an enlarged instream flow water right. The BLM is very interested in
protecting stream flows because Pauline Creek supports a diverse fishery and very healthy
riparian environment in an otherwise very arid location
Pauline Creek is 14.5 miles long. It begins on the northwestern flank of Stewart Peak in the La
Garita Wilderness at an elevation of approximately 13,100 feet and terminates at the confluence
with Cohcetopa Creek at an elevation of approximately 9,800 feet. Of the 4.1 mile segment
addressed by this report, 77% percent is located on federal lands. Pauline Creek is located within
Saguache County. The total drainage area of the creek is approximately 42.2 square miles.
Pauline Creek generally flows in a northeasterly direction.
The subject of this report is a segment of Pauline Creek beginning at the confluence with Chavez
Creek and extending downstream to the headgate of the Tarbell and Alexander Ditch, which is
immediately upstream of the confluence of Cochetopa Creek and Pauline Creek (see Map
Appendix D). The proposed segment is located southeast of the City of Gunnison. The staff has
received only one recommendation for this segment, from the BLM. The recommendation for
this segment is discussed below.
Justification for Enlargement
BLM has determined the existing Instream Flow regime, a single year-round discharge value, is
inadequate to protect the natural environment to a reasonable degree. This determination results
from an assessment of the importance of a snowmelt-dominated flow regime to, among other
things, the geomorphology of Pauline Creek. The single discharge value fails to provide for the
periodic higher flows needed to remove accumulated sediment and algal deposits, recharge
riparian groundwater, provide spawning trigger flows, and maintain adequate winter-period pool-
water exchange. As a result, BLM completed additional field data collection and concluded all
three of the flow factors considered (wetted perimeter, depth and velocity) had to be protected in
the Instream Flow Water Right. With the existing year-round flow only two of the target values
for these factors were regularly achieved. Only by increasing the ISF values could the three
factors, and the resulting geomorphic and biologic functions, be protected.
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