Laserfiche WebLink
<br />e <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 in the letter from BLM to the CWCB <br />"Fishery surveys indicate that the creek supports a self-sustaining brook trout fishery. The <br />stream environment is presently in good condition and provides suitable substrate, channel <br />stability, water quality, and food supplies for salmonids. However, the stream is very steep and <br />high velocity, so pools and other feeding/spawning locations are limited. Accordingly, it is <br />important to provide stream flows that maintain the limited amount of physical habitat and that <br />maintain water exchange in pools during low flow periods. (See BLM Fish Survey in Appendix <br />B). <br /> <br />Field Survey Data <br /> <br />BLM staff used the RfCross 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 !?roposed 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 CD OW 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 rraintained for most life stages of fish and aquatic invertebrates (Nehring <br />1979; Espegren 1996). I <br /> <br />I <br />I <br />For this segment of stream, two data sets were 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'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 /> <br />Table 1: Data <br /> <br />Party Date' Q 250%-40% Summer (3/3) Winter (2/3) <br />BLM 07/28/2004 2.55 1.0-6.4 1.57 1.53 <br /> , <br />BLM 07/28/2004 3.45 1.4 - 8.6 2.17 1.92 <br />BLM 07/28/2004 2.62 1.0-6.4 1.42 0.89~1) <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 />- 3 - <br />