INFLUENCE OF LAKE TYPE, SIZE, AND ECOREGION ON WATER QUALITY OF INLAND OHIO LAKES

As is the case throughout the midwestern United States, the lakes of Ohio are adversely impacted by widespread agriculture and mining practices. Lake type (natural, impoundment, or upground reservoir), size (acreage and maximum depth), and ecoregion (surrounding land use, vegetation, and local topography and geology) influence the extent to which lake chemistry is perturbed by human activity. This project explores whether the chemistry of 50 inland lakes throughout Ohio is most influenced by lake type, size, or ecoregional variation. Shallow and deep-water samples were analyzed to determine various parameters of water quality, including temperature, pH, conductivity, and nutrient concentrations (e.g., total phosphorus and nitrogen). Principal component analyses were performed on water quality data to determine whether lake chemistry is most similar in lakes of the same type, or in lakes in the same ecoregion. Preliminary analysis indicates that deep-water samples from lakes of the same type are more chemically similar than lakes from the same ecoregion. Lake type may be a strong determinant of lake chemistry in Ohio due to the relationship between lake type and catchment size. Most natural lakes in Ohio are kettle lakes with relatively small catchment sizes; thus, the volume of chemical inputs from runoff is relatively limited. Conversely, most impoundments have large catchment sizes, so these lakes receive large chemical inputs from their surroundings. Upground reservoirs have smaller catchments than natural lakes, as the former are raised above their surroundings. Future analyses are expected to reveal that impoundments cluster based on ecoregion, while natural lakes and upground reservoirs do not. This water quality data will also be used in conjunction with modern and historical diatom assemblage data from lake sediment cores to estimate the natural (pre-industrial) lake water quality of 8 inland Ohio lakes. Knowledge of the natural water quality of a lake can be used to determine the state to which a polluted lake can reasonably be restored.