OCR Text |
Show about 16.5 miles of Class III stream located on Ute Indian land. The habitat reduction would be expected to significatly reduce production of thriving populations of cutthroat, rainbow, brown and eastern brook trout as well as mountain whitefish. About 3,500 acre- feet of water stored in the reservoir would be released to maintain a minimum flow of 25 c. f. s. in Rock Creek where it enters Indian lands. ( Operational flows are discussed in detail in a later sub- section). Stream flow studies indicate that an average release of 8 c. f. s. at the dam together with accretions would produce the necessary 25 c. f. s. at the National Forest- Indian Reservation boundary. The Bureau of Sport Fisheries and Wildlife has estimated that the adverse impact of reduced flows on Rock Creek would eliminate about 75 percent of its recreational value as a fishery or about 71,800 man- days of fishing annually. Multilevel reservoir outlets to ensure that water to be released would be suitable for fish were not deemed necessary by the cooperating agencies. Large annual exchanges of water would be expected to ensure thorough mixing within the reservoir. Inundation and the reduction in stream flow would be expected to adversely affect the recreational boating potential on about 10 miles of presently suitable water. In addition to the fishery loss, the seasonal reduction of flows would be expected to adversely affect other biological aspects of the aquatic environment- particularly vegetation and invertebrates. Reduced discharges would lead to species changes within the popula tion of these organisms as current velocities would be reduced and water temperatures would be raised. Those species adapted to slower shallower water would expand at the expense of those that require fast water. The reduced stream flows would reduce populations of beaver, mink, songbirds, and other wildlife that require the existing type of streamside habitat. The artifically reduced flows would reduce habitat for amphibians and reptiles by eliminating marshy edges and reducing the number of available food organisms. Many of these species thrive best in moist areas along streams. Vegetational changes are expected to occur slowly as the new flow regime is implemented. Riparian plants would decrease in abundance as the soil moisture declines. There would be encroachment of the stream bed by terrestrial species. The reservoir would inundate about 340 acres of National Forest land that is presently relatively undisturbed. Adverse impacts include loss of present vegetative 218 |