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<br />measured discharge or under 40% of the measured discharge may not give an accurate estimate <br />of the necessary instream flow required. <br /> <br />Hydrologic Data <br /> <br />After receiving the cooperating agency's biologic recommendation, the CWCB and BLM staff, <br />conducted an evaluation of the stream hydTology to determine if water was physically available <br />fOT an instream flow appropriation. Although theTe is a substantial amount of stTeamflow gage <br />data available for the Uncompahgre Plateau and Glade Park, most of this data is seveTely <br />impacted by diversions and irrigation use. This situation makes it difficult to estimate the natural <br />flow regime for the watersheds on the Plateau. Without specific gage data to evaluate, the next <br />best approach is a regional equation that estimates annual flow characteristics. The USGS has <br />developed regional equations (Estimation of Natural Streamflow Characteristics in Western <br />Colorado. Water Resources Investigations Reoort 85-4086.1985) that apply to the Uncompahgre <br />Plateau and Glade PaTk based on basin drainage area, mean annual precipitation, mean basin <br />elevation and mean basin slope. The Teport "Uncompahgre Plateau and Glade Park Annual <br />Hydrograph Estimation" in Appendix C, explains staff's water availability analysis in mOTe <br />detail. Table 2 below displays the estimated stream flow ofPotteT Creek. <br /> <br />Table 2: Potter Creek estimated streamflow. <br /> <br />Janua FebRla March rll <br />1.4 3 4.4 66 <br /> <br />M. <br />242 <br /> <br />June <br />111 <br /> <br />Ju <br />5.7 <br /> <br />Au ust Sa tember October November December <br />2.2 1.8 1.7 1.7 1.5 <br /> <br />Potter Creek Estimated Stream Flow <br /> <br />5 <br /> <br />3 <br /> <br /> <br /> <br />4 <br /> <br />J!! <br />u <br /> <br />2 <br /> <br />1 <br /> <br />o <br /> <br />JAN <br /> <br />FEB <br /> <br />M<\R <br /> <br />APR <br /> <br />M<\Y <br /> <br />Jl.N <br /> <br />JL< <br /> <br />AUG <br /> <br />SEf' <br /> <br />OCT <br /> <br />NOlI <br /> <br />DEC <br /> <br />Month <br /> <br />Table 2 shows that the summer flow recommendation of 4.0 cfs is available from April 1 st <br />through July 31st. Table 2 also shows that the winter flow Tecommendation of 1.8 cfs is only <br />available from August 1st through September 14th and February 1st through March 31st. The <br /> <br />-4- <br />