Improved water quality in Ohio tributaries to Lake Erie: A consequence of conservation practices

Sediment is an important pollutant for Lake Erie and its tributaries, both as a carrier of other substances, particularly phosphorus, and as a pollutant in its own right. Environmental managers have called for major reductions in sediment and phosphorus loadings from Lake Erie tributaries. In this study, thirty-year datasets (Water Years 1975-2004) with daily resolution are analyzed to identify and interpret trends in suspended sediment and particulate phosphorus concentrations and loads in two major US tributaries to Lake Erie. The Maumee and Sandusky Rivers in agricultural northwest Ohio show continual decreases in concentrations and loads throughout this period. The greatest decreases are observed in summer and fall and under low flow conditions, whereas the smallest decreases are observed in the spring and under high flow conditions. Analysis of concentration-flow relationships indicates that these changes are not due to weather but reflect the successful use of agricultural practices to reduce erosion and prevent sediment loss. Opportunities for further reductions in suspended sediment and particulate phosphorus loads and concentrations lie in better management of sediment losses during winter and spring.