An assessment of streamflow, water quality, and the effects of constructing an impoundment on Bridge Creek at Augusta, Wisconsin

Abstract

This study documents Streamflow, temperature, and water-quality conditions of Bridge Creek at Augusta, Wisconsin, and evaluates the potential effects of a proposed small impoundment on the creek. The effects are of concern to the Wisconsin Department of Natural Resources because the stream is a Class II trout stream. Average daily Streamflow, from records collected during the 1980 water year, was about 50 cubic feet per second, and flow ranged from 4.5 to 1,010 cubic feet per second. Average summer (1980) water temperature of the creek was 21.0°C, and the average summer dissolved-oxygen concentration was 7.1 milligrams per liter. Water temperature did not exceed 26.0°C, and dissolved oxygen did not fall below 6.0 milligrams per liter at any time during the summer. A computer-simulated average summer temperature below the proposed impoundment was 22.5°C with a surface-level outlet from the reservoir, and 21.9°C with a bottom-draw outlet. Dissolved oxygen exceeded 6.0 milligrams per liter in both cases. Nutrient concentrations in Bridge Creek and comparisons with a similar impoundment at nearby Fall Creek indicate that the proposed impoundment would have nuisance weed growth. The impoundment would have a computed transit time of about 3 days, with a surface-level outlet, or 1 day with a bottom-draw outlet, assuming a normal pool elevation and a summer base flow of 7.5 cubic feet per second. Total storage in the proposed impoundment is estimated to be 48 acre-feet.