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DRAFT DRAFT DRAFT <br />deep pools in Reaches 2 and 3) support perennial occupation by native cutthroat <br />trout, but did support the native warm water fishes adapted to low-flow warm water <br />conditions. <br />B. MVIC -Dolores Project (1886-1986) Hydrology and Downstream <br />Ecology <br />Using the MVIC diversion data from CDSS (the same data that were added back <br />into the hydrologic record to simulate total flow at Bedrock in the last section), flow <br />conditions immediately below the MVIC diversions could be simulated for <br />representative dry, average, and wet water years (1974, 1978, and 1979 <br />respectively). Extreme dry and wet water years in 1977 and 1983 were avoided, <br />as they are less representative of expected variability. A detailed analysis and <br />discussion of MVIC effects on total flows, peak flows, and low flows is presented in <br />the larger "Correlation Report"; this section presents the hydrographs from that <br />analysis and summary conclusions about the resulting ecologic effects. <br />With the exception of a few cfs of bypass flows necessary to meet senior water <br />demands in Reach 1, MVIC's diversions took all the river's flow irregardless of <br />total flow for the year (figures 9-11). Because the scour functions of peak flows <br />were still occurring annually, tributary sediments were flushed, deep pools were <br />maintained through all reaches, and channel maintenance functions of high river <br />flows were preserved. Below Bradfield Bridge, the combination of seepage past <br />the MVIC diversions and occasional tributary inflow from ephemeral drainages <br />may have maintained some year-round flow, or at a minimum, standing water in <br />the deeper pools. Native warm water fish populations were able to persist, but <br />their numbers were probably annually limited by habitat availability during the dry <br />periods. Coldwater native species -specifically Colorado River cutthroat trout - <br />were probably not generally found below the MVIC diversion, although it is <br />possible that they occasionally occupied deep pool habitat within the upper three <br />reaches. <br />Cottonwood establishment and germination through Reach 1 was probably limited <br />to wet water years with good late-summer precipitation, when there was a gradual <br />water table recession beneath the sites where cottonwoods became established. <br />Early or rapid stream dry-up without supplemental rainfall would dessicate newly <br />established seedlings. <br />9/5/06 19 <br />