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Show pa T:r:;UfaFc?Flmino Ecrca Tdlv;stor-3 i (New Life for Flaming Gorge Tail-waters Tail-waters is adopted from an article by Bruce Schmidt which will appear in the JulyAugust issue of Utah Wildlife. - Ed.) Since 1962, when the gates at Flaming Gorge Dam were closed, millions have visited the reservoir. The Green River below the dam has also al-so received a great deal of attention. But fishing pressure pres-sure has fallen off in recent years. Although 35,000 people fished the Green in 1968, less than half that number fished last year. IN ORDER to understand the changes which occurred in the Green River, it is necessary to examine what happened when the dam was built. Before impoundment, the river was muddy and water levels fluctuated considerably con-siderably during the year. In winter, average flows were about 500 cubic feet per second (cfs), while average flows during spring runoff increased to 7,000 cfs. Temperatures also fluctuated, fluctuat-ed, ranging from freezing in the winter to above 70 degrees Fahrenheit in the summer. These unstable, muddy conditions con-ditions made the river unsuitable un-suitable for most sport fish. THE ONLY fish present were native species adapted to these conditions, such as the squawfish, razorback sucker and bonytail chub. Introduced In-troduced species like carp and channel catfish were also present. After construction of the dam, the silt carried by the river settled in the still waters of the new reservoir, and the Green River became crystal clear. The fluctuations in flow and temperature were also reduced. River flows are now governed by electric power generation, and average daily flows range from 1,300 to 2,800 cfs. High and low temperature extremes ex-tremes have been eliminated. FOR THE first few years following completion, winter water temperatures dipped only to 38 degrees and summer temperatures only reached 55 degrees. These clear, cold conditions made the river ideal habitat for trout, and the Division of Wildlife Resources began stocking when the dam was completed. For several years the Green River provided excellent fishing. The trout were large and most fishermen were ' leaving the river with full creels. BEFORE LONG, however, 'fishing success declined. Since the water intakes on the dam are stationary, 190 feet below the maximum high water level, only very cold water, not suitable for good . fish production, was entering the Green. The U.S. Bureau of Reclamation (BOR), which administers Flaming Gorge Dam, suggested that a hollow structure be built around each intake and extended toward the surface. THE BOR estimated that the water temperature could be raised eight degrees during dur-ing the summer by modifying two of the three intakes and 14 degrees by modifying all three. The BOR felt that if all three intakes were modified, temperatures would be within the range of good trout growth throughout the summer. THE THREE water-intake structures, now completed, are 220 feet long and 30 feet square. Water for power generation enters the structure struc-ture near the top through three gates, then flows down into the existing intake. During the summer, warm water will be drawn from a level near the surface; and in winter, water will come from . lower levels. THE MOST immediate result, obviously, has been warmer water temperatures in the Green River below Flaming Gorge Dam. With this warmer water will come increased primary production; produc-tion; that is, better growth of rooted plants and algae. These green plants are the first step in the aquatic food chain. Increased plant growth and the warmer temperatures will provide excellent food and growing conditions for small aquatic organisms such as mayflies and stoneflies, which are important food items for fish. THE IMPROVED conditions condi-tions for trout may not be ap- I parent to the angle: . season, however. Durmf first year of warmer rs , the numjfer of small a , J. the Rivrfr should intra w sincemigration ol sisL,, fingerling trout i, fwi reduced. f More trout in the ntFjL' faster growth will re.,-' greater angler succai -H season. The division o:" , that more and larger kil be caught in subsi l5" years. - |