2-08CW056 Supplemental Data - Laserfiche WebLink

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The information contained in this report and the associated appendices serves as the basis for the instream flow recommendation to be considered by the Colorado Water Conservation Board (Board). It is the professional opinion of the staff of both Trout Unlimited (TU) and the Colorado Division of Wildlife (CDOW) that the information described in these documents is sufficient for the Board's staff to begin the investigations required to establish an instream flow appropriation under Rule 5 i of the Instream Flow Rules. Severy Creek is approximately 4.0 miles long. It originates on the flank of Pike's Peak at approximately 11,500 feet and terminates at its confluence with Cascade Creek at an elevation of 8,400 feet (Fig 1). Of the 4.0 mile segment proposed for protection, approximately 75 %, 3.0 miles, is located U.S. Forest Service land and another 22% is held by Colorado Springs Utilities, a community owned utility (Table 1). Only 2.5% is in private ownership. Table 1: Severy Creek Land Status Review Upper Terminus Lower Terminus Total Length miles I Land Ownership % Private %USFS % CSU Headwaters above aqueduct 4.0 3% 76% 21% Instream Flow Recommendations TU and CDOW are recommending instream flow appropriations of 1.54 cfs during the summer and 0.79 cfs during the winter. These recommendations are based on the physical and biological data collected to date and does not incorporate any water availability constraints. An R2CROSS analysis of cross - sectional data collected on 7/28/06 was relied on to develop these recommendations (Table 2). Three instream flow hydraulic parameters, average depth, percent wetted perimeter, and average velocity, are used to develop biologic instream flow recommendations. The CDOW has determined that by maintaining these three hydraulic parameters at adequate levels across riffle habitat types, aquatic habitat in pools and runs will also be maintained for most life stages of fish and aquatic invertebrates (Nehring 1979; Espegren 1996). The modeling results from this effort were within the confidence interval produced by the R2CROSS model (Appendix B). Table 2: Severy Creek R2Cross Summary * Recommendations based on meeting specified number of hydrologic criteria (average depth, percent wetted perimeter and average velocity). Biological Data The CDOW has documented the occurrence of greenback cutthroat trout above a fish barrier on the lower portion of Severy Creek. This population has been shown to be genetically pure (Appendix B). This is significant because greenback cutthroat trout have been identified by the CDOW and federal agencies as "species of greatest conservation need" and are currently listed as "threatened" under the Endangered Species Act. Confidence Interval cfs Recommended Flows* cfs Party I Dat I Q cfs 250 % -40% Summer 3/3 1 Winter 2/3 TU 17/28/20061 0.87 1 2.2-0.3 1.54 1 0.79 * Recommendations based on meeting specified number of hydrologic criteria (average depth, percent wetted perimeter and average velocity). Biological Data The CDOW has documented the occurrence of greenback cutthroat trout above a fish barrier on the lower portion of Severy Creek. This population has been shown to be genetically pure (Appendix B). This is significant because greenback cutthroat trout have been identified by the CDOW and federal agencies as "species of greatest conservation need" and are currently listed as "threatened" under the Endangered Species Act.