Physical, chemical, and biological characteristics of Pueblo Reservoir, Colorado, 1985-89

Water-Resources Investigations Report 94-4097




Physical, chemical, and biological characteristics of Pueblo Reservoir, a main-stem, multipurpose reservoir on the Arkansas River, are described on the basis of data collected from 1985 through 1989. Water quality in the reservoir varies temporally and spatially as a result of seasonality of water quality in the Arkansas River, reservoir stratifi- cation, mixing and flow-through patterns, biological activity, and settling of particulate matter. Thermal stratification typically was strong from May into August. Fall turnover resulted in established well-mixed conditions throughout most of the reservoir from September or October into the spring. Water transparency increased downstream from the inflow as a result of settling of particulate matter. Anoxic conditions were measured in the hypolimnion on several occasions during the summer. The anoxic conditions resulted in relatively large releases of manganese from the bottom sediments into the water column. Concentrations of lead, mercury, and zinc in the bottom sediments were elevated compared to baseline values reported in the literature; metal-mine drainage in the upper Arkansas River Basin is a possible source of these metals. The median concentration of dissolved solids increased between the inflow and outflow from 224 milligrams per liter to 262 milligrams per liter. Phosphorus concentrations were low and potentially limiting to phytoplankton growth. Three species of phytoplankton that are associated with taste-and- odor problems in drinking-water supplies were observed at concentrations exceeding critical taste-and-odor threshold limits.

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USGS Numbered Series
Physical, chemical, and biological characteristics of Pueblo Reservoir, Colorado, 1985-89
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Water-Resources Investigations Report
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U.S. Geological Survey : USGS Earth Science Information Center, Open-File Reports Section [distributor],
v, 71 p. :ill., maps ;28 cm.