Laserfiche WebLink
<br />measured discharge or under 40% of the measured discharge may not give an accurate estimate <br />of ilie necessary instream flow required. <br /> <br />Hydrologic Data <br /> <br />After receiving ilie cooperating agency's biologic recommendation, ilie CWCB and BLM staff, <br />conducted an evaluation of the stream hydrology to determine if water was physically available <br />for an instream flow appropriation. Aliliough iliere is a substantial amount of streamflow gage <br />data available for ilie Uncompahgre Plateau and Glade Park, most of iliis data is severely <br />impacted by diversions and irrigation use. This situation makes it difficult to estimate ilie natural <br />flow regime for ilie watersheds on the Plateau. Wiiliout specific gage data to evaluate, the next <br />best approach is a regional equation iliat estimates annual flow characteristics. The USGS has <br />developed regional equations (Estimation of Natural Streamflow Characteristics in Westem <br />Colorado, Water Resources Investigations Report 85-4086, 1985) iliat apply to the Uncompahgre <br />Plateau and Glade Park based on basin drainage area, mean annual precipitation, mean basin <br />elevation and mean basin slope. The report "Uncompahgre Plateau and Glade Park Annual <br />Hydrograph Estimation" in Appendix C, explains staff's water availability analysis in more <br />detail. Table 2 below displays the estimated stream flow of Potter Creek. <br /> <br />Table 2: Potter Creek estimated streamflow. <br /> <br />Janua <br />1.4 <br /> <br />Februa <br />3 <br /> <br />March <br />4.4 <br /> <br />riI <br />66 <br /> <br />M, <br />242 <br /> <br />June <br />111 <br /> <br />J"' <br />5.7 <br /> <br />Au ust Se 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 />2 <br /> <br /> <br />:t2 <br />u <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 />JUN <br /> <br />JUL <br /> <br />AUG <br /> <br />SEP <br /> <br />OCT <br /> <br />NOV <br /> <br />CEC <br /> <br />Month <br /> <br />Table 2 shows iliat ilie summer flow recommendation of 4.0 cfs is available from April 15' <br />tlrrough July 315'. Table 2 also shows that ilie winter flow recommendation of 1.8 cfs is only <br />available from August 15' tlrrough September 14th and February 15' through March 315'. The <br /> <br />-4- <br />