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<br />. <br /> <br />. <br /> <br />USFWS - Palisade/Grand Junction Stream Flow Analyses - DRAFT <br />May 12, 1995 <br />'Page 2 ' <br /> <br />precipitation while in 1994 the precIpitation was below average. The following <br />observations have been made from the data. <br /> <br />1. On the average stream flows in 1994 were drier in August and September <br />compared to those recorded in 1991-1993 as shown below. The provisional 1994 <br />October through December flows are similar to the 1993 flows. Colorado River <br />flows in the critical reach were found to vary greatly between days and within <br />days. Average daily flows during the August through November period for all <br />years of data has been observed to range from approximately 350 cfs (1994) to <br />greater than 2,500 cfs. <br /> <br />Year July August September October November December <br />1991 NA 797 980 854 1,918 1,502 <br />1992 .. NA 822 801 629 1,644 1,417 <br />1993 NA 1,788 1,287 1,279 1,837 1,873 <br />1994 745 557 650 1.248 1,767 1,766 <br /> <br />Comparison of Gage Flows Entering 15 Mile Reach <br />Values in Average Daily CFS <br /> <br />Significant flow vanatlOn also occurs within days with the most significant <br />variations attributed to either precipitation events or operations of the local <br />irrigation company diversions. <br /> <br />2. When updating the 1993 provisional flow data with the official published records <br />by the USGS we observed that adjustments were upwards of 200 cfs and were not <br />consistent for the same river stage. We suspect that there may be some <br />"smoothing of the data" to reflect surrounding days of flow. This may be another <br />cause of the variability in daily calculated local inflows. It was also noted that <br />the Division Engineer's official 1993 diversiOli. records for the Government <br />Highline Canal do not reflect the period of no diversions in November. <br />3. Visual inspection of local inflow and local precipitation information indicates that <br />local precipitation events can contribute significant short term local runoff and <br />perhaps sustain local inflow during the non-irrigation season. The overall volume <br />of runoff produced from precipitation is probably small compared to irrigation <br />return flows in the area. <br />4. Additional data collected in 1994 supports last years belief that another cause of <br />calculated local inflow variation is due to the local operation of the Grand Valley <br />Project roller darn at Cameo for irrigation and power. Its operation can cause <br />