Stream: Cebolla Creek (Upper Segement) Executive Summary

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Biological Data This segment of Cebolla Creek is a moderate gradient stream, with moderate substrate size, punctuated by large boulders. The creek is sometimes confined by a narrow canyon, but in other locations the creek supports extensive wetland communities on a broad valley floor. The riparian community is in good condition and is composed primarily of willow -alder and spruce - fir communities. With a combination of large woody debris and occasionally large boulders in the creek channel, the creek provides good pool habitat for velocity cover and for overwintering. Sufficient riffle habitat for spawning does not appear to be a limiting factor for the fish population. 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 16 inches in length. The BLM has implemented trout habitat improvement projects within this reach. 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 biologic instream flow recommendations. The CDOW has determined that 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). For this segment of stream, five data sets were collected with the results shown in Table 1 below. Table 1 shows who collected the data (Party), the date the data was collected (Date), the measured discharge at the time of the survey (Q), the accuracy range of the predicted flows based on Manning's Equation (240% and 40% of Q), the summer flow recommendation based on meeting 3 of 3 hydraulic criteria and the winter flow recommendation based upon 2 of 3 hydraulic criteria. It is believed that recommendations that fall outside of the accuracy range of the model, over 250% of the measured discharge or under 40% of the measured discharge may not give an accurate estimate of the necessary instream flow required. -3-