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<br />. <br /> <br />. <br /> <br />. <br /> <br />Biological Data <br /> <br />The BLM has conducted field surveys of the fishery resources on this stream and have found a <br />natural environment that can be preserved, As reported for this reach of stream in the letter to <br />the CWCB "Fishery surveys indicate that the stream environment is in stable condition, and <br />supports a self-sustaining brook trout and rainbow trout fishery. Spawning substrate, pool <br />availability, and food availability are good for salmonids. However, cover is limited over this <br />wide stream, underscoring the importance of adequate flows to maintain sufficiently cool stream <br />temperatures during the summer and fall high temperature period. (See BLM Fish Survey in <br />Appendix B), In addition, Colorado Division of Wildlife has historically stocked this stream <br />with Colorado River Cutthroat Trout. <br /> <br />Field Survey Data <br /> <br />BLM staff used the R2Cross methodology to quantify the amount of water required to preserve <br />the natural environment to a reasonable degree. The R2Cross method requires that stream <br />discharge and channel profile data be collected in a riffle stream habitat type, Riffles are most <br />easily visualized as the stream habitat types that would dry up first should streamflow cease. <br />This type of hydraulic data collection consists of setting up a transect, surveying the stream <br />channel geometry, and measuring the stream discharge, Appendix B contains copies of field <br />data collected for this proposed segment. <br /> <br />Biological Flow Recommendation <br /> <br />The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret <br />output from the R2Cross data collected to develop the initial, biologic instream flow <br />recommendation. This initial recommendation is designed to address the unique biologic <br />requirements of each stream without regard to water availability. Three instream flow hydraulic <br />parameters, average depth, percent wetted perimeter, and average velocity, are used to develop <br />biologic instream flow recommendations. The CDOW has determined that maintaining these <br />three hydraulic parameters at adequate levels across riffle habitat types, aquatic habitat in pools <br />and runs will also be maintained for most life stages of fish and aquatic invertebrates (Nehring <br />1979; Espegren 1996), <br /> <br />For this segment of stream, one data set was collected with the results shown in Table 1 below. <br />Table 1 shows who collected the data (Party), the date the data was collected (Date), the <br />measured discharge at the time of the survey (Q), the accuracy range of the predicted flows <br />based on Manning Equation (240% and 40% of Q), the summer flow recommendation based on <br />meeting 3 of 3 hydraulic criteria and the winter flow recommendation based upon 2 of 3 <br />hydraulic criteria. <br /> <br />Table 1: Data <br /> <br />Party Date Q 250%-40% Summer (3/3) Winter (2/3) <br />BLM 10/15/98 15,9 39.8 - 6.4 11.3 10.4 <br /> , , , <br /> <br />BLM = Bureau of Land Management DOW = DIvIsIOn of WIldlIfe <br />(I) Predicted flow outside of the accuracy range of Manning's Equation, ? = Criteria never met in R2CROSS Staging Table. <br /> <br />Biologic Flow Recommendation <br />The summer flow recommendation, which meets 3 of 3 criteria and is within the accuracy range <br />of the R2CROSS model is 11.3 cfs (See Table 1). The winter flow recommendation which <br />meets 2 of 3 criteria and is within the accuracy range of the R2CROSS model is 10.4 cfs (See <br />Table 1), <br /> <br />- 4- <br />