OCR Text |
Show represents an average reduction in winter flow of 30 to 60 percent in the 10 miles of stream between Jordanelle and Deer Creek Reservoirs. In the early irrigation season ( spring) the reach of the river above Jordanelle Reservoir would remain unchanged except for a small increase resulting from runoff previously stored in 15 high mountain reservoirs that under Unit conditions would be stabilized. The irrigation function of these reservoirs would be taken over by Jordanelle Reservoir. At Jordanelle Reservoir the high runoff flows including imported water from the Duchesne and Weber Rivers along with some natural flow would be stored. This impoundment of water would result in a reduction of the existing undesirable high peak flows between Jordanelle Reservoir and Deer Creek Reservoir of 25 to 40 percent. This reduction in flow would lessen the adverse impacts presently caused by excessive peak discharges. During the late irrigation season, the river above the Washington- South Kamas Canal would be essentially unchanged. Under Unit conditions, additional water would be diverted from the river at this point to supply lands in the Francis- Kamas area by exchange with Jordanelle Reservoir. As a consequence, there would be about a 30- percent reduction in the flow in the 14 miles of stream immediately above the reservoir. Flows in the entire reach above Jordanelle Reservoir may, at times, be less than historically slow because of late summer demands which ware previously satisfied with water from the high mountain reservoirs. The river flows below the reservoir would be substantially higher than those occurring under pre- Unit conditions. The increases would result from Unit municipal, industrial, and irrigation releases; prior- right irrigation bypasses; return flows from the Heber area; and the guaranteed fishery release of 50 c. f. s. The net result of the Bonneville Unit's impact on the Upper Provo River would be moderate reduction in summer fishery habitat above Jordanelle Reservoir and a substantial improvement in the situation below the reservoir,, The Unit operations would significantly reduce excessive spring flows and increase late summer flows that at present periodically approach complete dewatering* |