OCR Text |
Show power water would be conveyed southward by the Wasatch Aqueduct for reregulation in Mona Reservoir Enlargement, to Sevier River Basin, or for use at intermediate points. Dyne Powerplant would be located 500 feet upstream from the confluence of Sixth Water Creek and Diamond Fork, and the intake structure of Wasatch Aqueducts would be located in the tailrace of Dyne Powerplant. At the latter point, 97,800 acre- feet of the imported water from Strawberry Reservoir would be diverted into Wasatch Aqueduct and the remaining 99,800 acre- feet would be conveyed in Diamond Fork Channel to Hayes Reservoir. The daily flows through Dyne Powerplant would be in the 200- to 600- c. f. s. range. Up to 200 c. f. s. of this flow would be diverted into the Wasatch Aqueduct and the remaining discharge would be carried by Diamond Fork. As a result, the flows in the 5- mile reach of Diamond Fork above Hayes Reservoir could have an average daily fluctuation between 80 and 400 c. f. s. throughout much of the year. The planned operation would have peak flows occurring twice per day and would be achieved within a period of 10 minutes. A Forest Service 70 analysis' indicated that in order to ensure channel stability, flows exceeding 300 c. f. s. should not be allowed. This report also stated that the most desirable flow rate would be approximately 130 c. f. s. which is the historic maximum mean monthly discharge. At this flow very little available streambed material would be moved and the aquatic habitat and fishery potential would be improved. According to the Forest Service, artificial flows should not vary more than 25 percent of the mean if stability of the channel is to be realized. It has been estimated that the average daily flows would be in the 80- to 325- c. f. s. range. Under the existing Strawberry Irrigation System, flows in this same reach usually ranged up to 537 c. f. s. for long periods during the irrigation season. The maximum recorded flow in Diamond Fork near Hayes Reservoir site was 1,610 c. f. s„ on May 4, 1952. -^ a |