Laserfiche WebLink
<br />sensitive cool water fishes, such as long-nose sucker. Channel stability, bank stability, and <br />substrate are good for supporting a fish population. However, the fishery is limited by lack of <br />cover in some locations, and by occasional high temperatures and low stTeam flows. <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 assuTed" (See BLM Fish Survey in <br />Appendix B). <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 enviTonment to a reasonable degree. The R2Cross method requires that stream <br />discharge and channel profile data be collected in a riffle stTeam 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 wateT availability. Three instream flow hydTaulic <br />parameters, average depth, percent wetted perimeter, and aveTage 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 fOT most life stages of fish and aquatic invertebrates (Nehring <br />1979; Espegren 1996). <br /> <br />For this segment of stream, two data sets were collected with the results shown in Table I below. <br />Table I 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 summeT 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 I: Data <br /> <br />Party Date Q 250%-40% Summer (3/3) Winter (2/3) <br />BLM 6/05/2003 1.94 4.7 -0.8 5.1\'1 1.5 <br />BLM 6/04/2003 2.11 5.1 - 0.8 4.0 2.1 <br /> <br />BLM = Bureau of Land Management DOW = DIVISIOn of Wlldhfe <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 4.0 cfs (See Table I). The winter flow recommendation, which meets <br />2 of 3 criteria, is 1.8 cfs. The winter recommendation is the result of averaging two modeling <br />runs that were within the accuracy range of the R2CROSS model (See Table I). It is our belief <br />that Tecommendations that fall outside of the accuracy range of the model, over 250% of the <br /> <br />- 3 - <br />