7137 - Laserfiche WebLink

Home Browse Search

22. During periods of high inflow, discharge in excess of the 4200 cfs (combined capacity of hydropower units) can be released through flood gates located on the top of the dam or through river outlets (hollow jet valves) which are conduits through the dam located at roughly 297 ft depth. Water temperature at the river outlet withdrawal depth and in the 40-190 ft stratum from which the hydropower units withdraw water is cold year-round rising slightly by late summer from the near 390E normally experienced in the coldest months. Obviously, increased discharge-and a greater proportion of total discharge coming from this depth results in lowered water temperatures downstream during the warmer months. Figure 15 shows the total discharge from Flaming Gorge Dam partitioned by source for the period June-August, 1983. The effects of cold water release and power peaking flows decrease with distance from the dam, but undoubtedly alter the seasonal water.temperature pattern and flow regime for a considerable distance downstream. The relationship between the Green River hydrograph and Colorado squawfish recruitment, evaluated in this report, indicates that a negative relationship exists between late summer and fall discharge and successful recruitment of Colorado squawfish. It will require close cooperation between the Bureau of Reclamation, Fish and Wildlife Service and cooperators in the future, to more adequately determine the relationship between flows released from Flaming Gorge Dam and the needs of endangered fishes in the Green River Basin. -It is suggested that discharge be controlled in 1985 to duplicate flows favorable to Colorado squawfish larval growth and survival. FWS should have input into planning a 1985 release strategy designed to enhance Colorado squawfish reproductive success. The importance of a successful 1985 year class cannot be overemphasized since recruitment in 1983 and 1984 was negligible.