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<br />liberalized when chumming with dead anchovies was allowed to <br />increase harvest of striped bass in 1996 and the simultaneous use <br />of two fishing rods was allowed with the purchase of a 2-pole <br />fishing stamp in 1997. <br /> <br />STUDY AREA <br /> <br />Lake Powell is impounded by Glen Canyon Dam on the Colorado <br />River, 9.7 km south of the Utah/Arizona border (Figure 1). The <br />300 km-Iong reservoir is confined to the deep narrow canyon of <br />the Colorado River and its tributaries. Most of the 2,930 km of <br />shoreline is comprised of sandstone cliffs and talus slopes. <br />Only a few side bays offer relief from the towering vertical <br />canyon walls. Average depth of the reservoir is 50.9 m (Johnson <br />and Merritt 1979) with maximum capacity at 3.32X108 m3. <br />Lake Powell is a warm meromictic reservoir with <br />stratification generally beginning in April and persisting into <br />December. The deepest water below penstock levels seldom mix <br />with the active upper layers which are greatly influenced by a <br />lake-long density current. Main channel pelagic surface <br />temperatures range between extremes of 6.7 and 29.4 C. <br />Visibility is typically 3-9 m although secchi disk readings as <br />high as 14 m have been recorded by UDWR personnel. Chlorophylla <br />normally ranges from 1.8-2.5 ug/l with levels as high as 5 <br />occurring in isolated locations (Paulson and Baker 1983, <br />Sollberger et ale 1989). Plankton densities seldom exceeded 20/1 <br />in main channel locations (Sollberger et al. 1989) with higher <br />densities found where major tributaries enter the reservoir and <br />in side canyons with perennial streams or flash flood events <br />increase nutrient loading. Fluctuating lake levels cause <br />redistribution of nutrients trapped in lake bottom sediments that <br />are exposed as water levels decline. Constantly flowing <br />tributaries or storm events cut through the sedimentary layers <br />and wash sediment and nutrients back into the reservoir where <br /> <br />7 <br />