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<br />e: <br /> <br />. <br /> <br />. <br /> <br />Biological Flow Recommendations <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 />DOW /CWCB 10/8/96 0.28 0.7 - 0.1 1.4~1) 0.65 <br /> <br />BLM = Bureau of Land Management DOW = Division of Wildlife <br />(I) Predicted flow outside of the accuracy range of Manning's Equation. <br /> <br />CWCB = Colorado Water Conservation Board <br />? = Criteria never met in R2CROSS Staging Table. <br /> <br />Biologic Flow Recommendations <br />The CDOW recommended a 0.65 cfs summer/winter flow for the segment based on the October <br />8th, 1996, data collection efforts. <br /> <br />Staff reviewed the data collected by the CDOW. The summer flow recommendation for the <br />proposed reach, which meets 3 of 3 criteria but is outside the accuracy range of the R2CROSS <br />model is 1.4 cfs. The winter flow recommendation for the proposed reach, which meets 2 of 3 <br />criteria and is within the accuracy range of the R2CROSS model is 0.65 cfs (See Table 1). It is <br />our belief that recommendations that fall outside of the accuracy range of the model, over 250% <br />of the measured discharge or under 40% of the measured discharge may not give an accurate <br />estimate of the necessary instream flow required. In these cases, CWCB staff relies upon the <br />biological expertise of the cooperating agencies to develop a biologic instream flow <br />recommendation. <br /> <br />The CDOW has indicated that this is a high priority stream segment to them. However, because <br />the summer recommendation falls outside the accuracy range of the R2CROSS model, staff <br />believes that more data needs to be collected to accurately predict the summer flow <br />recommendation. Staff has consulted with the recommending agency and believes that it would <br />be appropriate for the Board to file on a year-round flow of 0.65 cfs, if water was available (See <br />Table 1). <br /> <br />Hydrologic Data <br /> <br />After receiving the cooperating agency's biologic recommendation, the CWCB staff conducted <br />an evaluation of the stream hydrology to determine if water was physically available for an <br />instream flow appropriation. There are no currently operated or historically operated streamflow <br />gages for this reach. The closest gage CWCB staff found was the gage located on the San <br /> <br />- 4 - <br />