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INTRODUCTION <br />Flaming Gorge Reservoir is located at approximately 41° north latitude and <br />109° west longitude in southwest Wyoming and northeast Utah (Figure 1). Maximum <br />surface elevation is 6,040 feet above mean sea level, with a mean depth of 111 <br />feet, maximum surface area of 42,000 acres and it is 91 miles long. Maximum <br />depth near the dam is 440 feet. The reservoir was built on the Green River by <br />the Bureau of Reclamation and began impounding water in November 1962. <br />The reservoir has been divided into three distinct study areas (Figure 1) <br />based upon studies of trout growth (Varley, Regenthal, and Wiley 1971a), <br />topography, geology, and hydrographic features (Eiserman and Stone 1979), plank- <br />ton (Varley 1967), distribution of fishes, benthic organisms, and diet of salmo- <br />nids (Eiserman et al. 1967; Wiley and Varley 1975). The three areas are the <br />Inflow, Open Hills, and Canyon. <br />The Inflow Area is the northern 39 miles of the reservoir influenced <br />directly by the Green and Black's Fork Rivers (Figure 1). The southern boundary <br />was moved approximately two miles south in 1978 to accommodate aerial fishermen <br />counts providing definitive demarcation for recognition. Typically the area is <br />turbid during spring run-off with high summer water temperatures and poor <br />dissolved oxygen quantities in the cooler water temperature stratum preferred by <br />salmon.ids. The fishery is characterized by extensive rough fish populations. <br />However, during the spring, fall, and winter, when the reservoir cools, large <br />brown and lake trout are attracted by the abundant forage in this highly produc- <br />tive (eutrophic) area. <br />The Open Hills Area extends approximately 28 miles south to the entrance of <br />the Flaming Gorge (Figure 1). The Open Hills habitat can be classified as a <br />transition zone between,the eutrophic Inflow and the oligotrophic Canyon Area. <br />The area is characterized by gently sloping shorelines and low, rolling <br />sagebrush covered hills. The moderate depths (ranging to 200 feet), extensive <br />littoral bay areas and clear water make this area prime habitat for pelagic <br />sport fish, large lake trout and smallmouth bass. <br />The Canyon Area is the southern most area of the lake. The Canyon extends <br />from Flaming Gorge for about 24 miles to the dam near Dutch John, Utah. The <br />habitat of the Canyon is characterized by steep rock walls and deep, clear, <br />seasonally stratified water with limited littoral area. Water in the Canyon <br />Area is described as oligotrophic. Sport fish populations are highest in the <br />Canyon, however, their condition factors are the lowest of the three reservoir <br />zones. <br />The Green River drainage was treated with rotenone to depress undesirable <br />fish species in 1962 prior to the closure of Flaming Gorge Dam. This project <br />encompassed 445 miles of the Green River and its tributaries and resulted in the <br />reduction of fish life at all trophic levels (Eiserman and Stone 1979). <br />Publications which related to the chemical, biological and physical features of <br />the river environment prior to and after the rotenone treatment of the Green <br />River have been written (Bosley 1960; McDonald and Dotson 1960; Binns et al. <br />1963; Binns 1967; Henderson 1963; Vanicek and Pearson 1967). <br />Rainbow trout (Salmo gairdneri) were first planted in the new reservoir in <br />April of 1963 (Eiserman et al. 1963) and provided an excellent "family-type" <br />-1-