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Biological Data The CDOW has conducted field surveys of the fishery resources on this stream and have found a natural environment that can be preserved. As reported for this reach of stream in CDOW'S recommendation letter to the CWCB, "Cornet Creek was sampled using standard electrofishing equipment approximately 118 mile above the confluence with the San Miguel River. The aquatic sampling summary (See CDOW Fish Survey in Appendix B - on the field data sheet) shows that a self sustaining brook and brown trout fishery exists in Cornet Creek. Cornet Creek also has a healthy aquatic macroinvertebrate population indicative of high quality water. Cornet Creek also supports a healthy riparian community. Instream flows are needed to preserve and protect these biological communities in addition to the existing brook and brown trout fishery. Cornet Creek also produces high quality water that serves to provide assurance that mine clean-up activities in the upper San Miguel basin (above the Town of Telluride) will continue to show improvements to the river's water quality and the river's fish population." Field Survey Data CDOW and CWCB 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. Appendix B contains copies of field data collected for this proposed segment. Biological Flow Recommendations 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 in stream 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, one data set was collected with the results shown in Table I below. Table I 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 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. Table I: Data Party Date Q 250% -40% Summer (3/3) Winter (2/3) DOW/CWCB 10/08/96 3.93 9.8 - 1.6 9.0 3.5 BLM = Bureau of Land Management DOW = Division of Wildlife (1) Predicted flow outside of the accuracy range of Malll1ing's Equation. CWCB = Colorado Water Conservation Board ? = Criteria never met in R2CROSS Staging Table. Biologic Flow Recommendations The CDOW recommended a 9.0 cfs summer flow and a 3.5 cfs winter flow based on the October 8, 1996, data collection efforts. Staff reviewed the data collected by the CDOW. The summer - 3 -