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DRAFT DRAFT DRAFT <br />interaction with its floodplain. The introduction of tamarisk into the Dolores <br />River watershed probably dates back to the 1930s -1950s. However, even <br />as tamarisk began invading during this period, according to a joint agency <br />report, "Cottonwoods remain the dominant tree, especially notable in large <br />groves through the Gypsum Valley" (CO DNR, U.S. DOI, 1976). <br />WY 1979 - "Wet Year" <br />8000 <br />7000 <br />6000 <br />r. 5000 <br />N <br />U <br />U! <br />~+ 4000 <br />A <br />t <br />U <br />N <br />0 3000 <br />2000 <br />1000 <br />-Flow blw MVIC -Flow @ Cblores -Flow @ Bedrock <br />Figure 11. Calculated flow below the MVIC diversions, and gage data from <br />Dolores and Bedrock gages for WY 1979. Note scale change on vertical <br />axis. <br />Table 2 immediately below summarizes largest, smallest, and average run-off <br />volumes into McPhee, MVIC diversions, and flow-by river volumes with MVIC <br />diversions. This table is based on historic flow data and MVIC diversion data from <br />1928 to 1973. <br />Table 2: Comparison of Flow-by with MVIC Diversions <br />1928-1973 Largest Smallest Average <br />Run-Off Volume 793K of 130K of 350K of <br />MVIC Only <br />MVIC Diversions 150K of 64K of 131 K of <br />Flow-by (occurs every year) 643 K of 28K of 219K of <br />Flow-by as % of run-off vol. 81 % 22% 63% <br />As the flow-by line highlighted in green in Table 2 indicates, the volume of water <br />during the driest year (28K af) is close to the fish pool (29.3K af) that will be <br />described in the Dolores Project period write-up below, but as the `dry-year' <br />hydrograph shows (Figure 9), flow-by in dry years occurred prior to mid-June, <br />leaving extended periods during the summer when the River did not flow except <br />9/5/06 21 <br />0 <br />10/13 12/2 1/21 3/12 5/1 6/20 8/9 9/28 11/17 1/6 <br />