Stream: Cochetopa Creek (Lower Segement) Executive Summary

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when the fish population requires more physical habitat for foraging, weight gain, and preparation for the fall spawning period. If the current instream flow water right were to be experienced during snowmelt runoff, less than 2/3 of the active stream channel would be wetted. With this reduction in physical habitat, the creek would not be able to sustain the fish biomass it sustains today. Instream Flow Recommendation The BLM recommended 6.8 cfs (May 1 to November 15). This recommendation was based on their data collection efforts and staff's water availability analyses. Land Status Review Upper Terminus Lower Terminus Total Length (miles) Land Ownership % Private % Public Confluence w/ Alkali Creek Headgate of South Krueger Ditch 12.92 40% 60% 100% of the public lands are managed the by the BLM. Biological Data This segment of Cochetopa Creek is a moderate to high gradient stream, with moderate to large substrate size, punctuated by large boulders. Most of the proposed reach is confined by a narrow canyon, and is further confined by the construction and maintenance of State Highway 114. The riparian community is in good condition and diverse, composed of alder, willow, and red osier dogwood. The riparian community often provides good shading for the water column. The presence of alder indicates a very reliable flow regime and consistent groundwater level in the alluvial aquifer. The creek provides an excellent mix of pools, riffles, and runs for fish habitat. BLM has invested in fisheries habitat improvement projects in this section of the creek, just downstream from Alkali Creek. Fishery surveys indicate that the creek supports a self - sustaining population of brown trout. The survey revealed a variety of age classes and individual specimens up to 12 inches in length. Field Survey Data BLM staff used the R2Cross methodology to quantify the amount of water required to preserve the natural environment to a reasonable degree. The R2Cross method requires that stream discharge and channel profile data be collected in a riffle stream habitat type. Riffles are most easily visualized, as the stream habitat types that would dry up first should streamflow cease. This type of hydraulic data collection consists of setting up a transect, surveying the stream channel geometry, and measuring the stream discharge. Biological Flow Recommendation The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret output from the R2Cross data collected to develop the initial, biologic instream flow recommendation. This initial recommendation is designed to address the unique biologic requirements of each stream without regard to water availability. Three instream flow hydraulic parameters, average depth, percent wetted perimeter, and average velocity are used to develop -3-