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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 instream 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 determined that maintaining these three 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 invertebrates (Nehring 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 Manning 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 Date 6/22/94 Q 2.01 250%-40% 5.02 - 0.8 Summer 2.75 Winter 2/3 1.90 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 R2CROSS Staging Table. Biologic Flow Recommendation The BLM recommends 2.75 cfs summer flow and 1.90 cfs winter flow based on its survey conducted on June 22, 1994. Both the summer and winter recommendations are within the confidence interval produced during the R2Cross modeling effort (see Table 1). . Hydrologic Data After receiving the cooperating agency's biologic recommendation, the CWCB staff conducted an evaluation of the stream hydrology to determine if water was physically available for an instream flow appropriation. There are no currently operated or historically operated streamflow gages for this reach. The closest gage CWCB staff found was the gage located on Roc Creek 7.1 miles southwest of the Mesa Creek drainage. The hydro graph below was derived from data collected by the USGS stream gage for Roc Creek near Uranium, CO (ID #09179000), which has a drainage area of 75.8 square miles. The drainage area upstream of the Cedar Tree Ditch is approximately 27.5 square miles. Staff used a basin apportionment method to estimate stream flows for North Fork Mesa Creek (See Gage Summary in Appendix C). The period of record for this gage was 1944 to 1952, the period of record used by staff in their analysis was 1944 - 1952, or eight years of record. Table 2 below displays the estimated flow of South Fork Mesa Creek, in terms of a percentage of exceedence.