Nutrient loadings to Mill Creek Watershed and Lake Newport

Abstract

Estimates of external nutrient loadings were made for Lake Newport, a shallow extremely productive (hypereutrophic) lake in Mill Creek Park, Youngstown, Ohio, to provide a basis for lake management decisions. Mill Creek drains a watershed area of about 73.85 square miles. Runoff contributes large nonpoint nutrient loading to the Mill Creek system and Lake Newport. In addition, the Boardman Wastewater Treatment Plant discharge contributes major point source nutrient loading. Primarily empirical models or simple deterministic models oftrophic status were applied to Lake Newport. Determination of only a few parameters were required. Field sampling was performed during July to October 1994; temperature, dissolved oxygen ammonia, nitrate, suspended solids, 5-day BOD and both total and soluble reactive phosphorus were determined. A detailed analysis was done on 1993 NPDES monitoring data from the Boardman Wastewater Treatment Plant. Many hydrologic and morphometric parameters were calculated for Lake Newport. Lake Newport's trophic status was predicted to be hypereutrophic using Vollenweider's (1975) loading plot. Also, Dillon and Rigler's (1975) method was used to estimate the total phosphorus loading. It was also estimated that if the sewage effluent (major point source) is minimized, it is likely that the lake would still remain hypereutrophic, but the water quality should improve significantly. Also, the data collected in this study can be used for more detailed water quality modeling.