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"Fishery surveys indicate that the stream environment is presently in stable condition, and <br /> supports a self-sustaining brook trout fishery. Channel stability, bank stability, and water quality <br /> are good for salmonids. However, limiting factors in this reach include a limited supply of <br /> spawning substrates and pools, along with occasional low flows and high stream temperatures. <br /> Accordingly, it is important to provide stream flows that protect the limited amount of available <br /> habitat if the continued existence of the fishery is to be assured" (See BLM Fish Survey in <br /> Appendix B). <br /> Field Survey Data <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 /> Biological Flow Recommendation <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 /> For this segment of stream, three data sets were collected with the results shown in Table 1 <br /> below. 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's Equation (240% and 40% of Q), the summer flow recommendation based <br /> on meeting 3 of 3 hydraulic criteria and the winter flow recommendation based upon 2 of 3 <br /> hydraulic criteria. <br /> Table 1: Data <br /> Party Date Q 250%-40% Summer (3/3) Winter(2/3) <br /> BLM 6/24/1997 8.57 22.3 —3.6 1.9(1) 1.2(1) <br /> BLM 10/15/2004 1.00 0.4—2.5 2.4 1.30 <br /> BLM 10/15/2004 1.05 0.4—2.6 ? 0.7 <br /> BLM=Bureau of Land Management DOW=Division of Wildlife <br /> (1)Predicted flow outside of the accuracy range of Manning's Equation. ?=Criteria never met in R2CROSS Staging Table. <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 2.4 cfs (See Table 1). The winter flow recommendation, which meets <br /> 2 of 3 criteria and is within the accuracy range of the R2CROSS model, is 1.0 cfs if the two <br /> within-range results are averaged (See Table 1). It is our belief that recommendations that fall <br /> - 3 - <br />