ISFAPPC03885 - Laserfiche WebLink

Home Browse Search

. . . Biological Data The BLM 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 the letter to the CWCB "Fishery surveys indicate that the stream environment is in stable condition, and supports a naturally reproducing Colorado River cutthroat trout population. Food availability and vegetative cover are good for salmonids, but pool habitat and spawning habitat is a limiting factor because of the steep gradient. The paucity of pool habitat and spawning habitat underscores the importance of protecting sufficient water for maintaining the limited physical habitat" (see CD OW Fish Survey in Appendix B). 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. Appendix B contains copies of field data collected for this proposed segment. 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 instrealiJ.1 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 detemlined that maintaining these tlu'ee 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 inveliebrates (Nelu'ing 1979; Espegren 1996). For this segment of stream, one data set was 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 Mmming 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 1: Data Party BLM Summer (3/3) ? Date 5/19/1999 Q 0.53 0.43 250%-40% 1.3-0.2 1.1-0.2 Winter (2/3) 0.3 0.4 BLM 9/08/2000 ? BLM Bureau of Land Management DOW - Division of Wildlife (I) Predicted flow outside of the accuracy range of Manning's Equation. ? = Criteria never met in RlCROSS Staging Table, Biologic Flow Recommendation The summer and winter flow recommendation, which meets 2 of 3 criteria and is within the accuracy range ofthe R2CROSS model is 0.35 cfs (See'Table 1). - 3 -