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<br /> <br />Water in the reservoir and in the White River was a hard to very hard <br />calcium. bicarbonate type during high runoff and a very hard calcium magnesium <br />sulfate bicarbonate type during low flow. :A change in, ionic composition to a <br />mixed cation sulfate type is predicted during extremely low-flow conditions <br />when specific-conductance values exceed 1,000 microsiemens per centimeter. <br />Concentrations of nitrogen and phosphorus were greatest during spring runoff, <br />least in periods of low flow, and were sufficient to support nuisance phyto- <br />plankton growths. Concentrations of ammonia as nitrogen were as much as <br />0.13 milligram per liter during summer in near-bottom depths at the dam. <br />Concentrations of 22 trace constituents generally were less than maximum <br />recommended concentrations established by the State of Colorado for cold-water <br />biota. <br /> <br />A total of 210 phytoplankton species from 7 phyla were identified in <br />Kenney Reservoir. Phytoplankton were mostly bacillariophyta (diatoms) and <br />chlorophyta (green algae) in 1985-86 and cyanophyta (blue-green algae) in <br />1987. Cell counts increased from the inflow site to the dam site. Except for <br />an algae bloom in June 1987, a maximum combined cell count (unrounded value) <br />of greater than 15,000 cells per milliliter occurred in a composite sample at <br />the dam in July 1986. In June 1987, a phytoplankton bloom that had cell <br />counts of 71,000 cells per milliliter and that consisted mostly of the <br />dinoflagellate, peridinium biceps, developed in the reservoir. Similar blooms <br />may occur in the future when concentrations of nutrients are large and when <br />inflow to the reservoir during summer is low. Bacteria concentrations ranged <br />from less than 2 to 1,100 colonies per 100 milliliters. Ratios of fecal <br />coliforms to fecal streptococci generally were less than 1.0. <br /> <br />Suspended-sediment loads at the White River upstream from the reservoir <br />during 1983-87 ranged from 391,000 to 1,570,000 tons per year. Bedload was <br />less than 1.2 percent of the suspended-sediment load. Sediment retention in <br />Kenney Reservoir was estimated to range from about 91 to about 98 percent. <br />Calcula,tions for estimated volume displacel11ent resulting from sediment <br />deposition during 1985-87 ranged from about 1.8 to about 5 percent of the <br />original capacity of the reservoir per year. <br /> <br />INTRODUCTION <br /> <br />During 1984, Kenney Reservoir was constructed in the White River basin in <br />northw~stern Colorado (fig. 1). rhe reservoir, which has a small capacity <br />(13,800 acre-ft), is located on the White River about 8 mi northeast of <br />Rangely. The name of the reservoir originally was proposed to be Taylor Draw <br />Reservoir but later was renamed Kenney Res~rvoir after the completion of <br />Taylor Draw Dam. The dam is a reinforced earth type and has a spillway <br />capacity of 65,300 ft3/s at a crest elevation of 5,317.5 ft. A second outlet <br />that has a capacity of 1,700 ft3/s is provided through an intake orifice near <br />the reservoir bottom at 5,270 ft. When the reservoir is full, the surface <br />area is 615 acres and the maximum depth ne~r the dam is about 50 ft. <br /> <br />The construction of Taylor Draw Dam and filling of Kenney Reservoir were <br />done in response to increased water-management needs in northwestern Colorado. <br />The main purposes of the reservoir were to. provide local water supply, <br />recreational use, and potential hydroelectric production. Secondary purposes <br />included flood control and stream water-quality improvement. <br /> <br />2 <br />