The objective of this study was to determine changes in the chemical composition of water that result from its use by the town of Bucyrus in Crawford County, OH, and to document the effect of the discharge of wastewater on the quality of water in the Sandusky River. The results indicate that the wastewater is enriched in the major elements (Na, K, Mg, Ca, and Sr) compared to tap water in the town of Bucyrus. However, the treated wastewater does not significantly alter the chemical composition of water in the Sandusky River represented by a ten-year average from 1984 to 1994. The concentrations of Mo in raw water and in the wastewater are nearly identical, which means it cannot have an anthropogenic source. The wastewater does not contain P because this element is effectively removed as required by the Great Lakes Water Quality Agreement.