Comparison of six lakes in Cheboygan and Presque Isle Counties,

To detect and avoid serious water quality issues, it is imperative to monitor trophic state and nutrient status within a lake. Lake comparisons can serve as a useful tool for understanding the factors affecting lake conditions through an examination of similarities and differences of various parameters within different lakes, as well as the differences in lake conditions affected by these various parameters. In this study, nutrient, light, and chlorophyll a concentrations in six lakes in Cheboygan and Presque Isle Counties, Michigan, were measured and compared. Trophic state was also considered using Carlson’s (1977) Trophic State Index (TSI). Differences in productivity and nutrient concentrations were expected based on physical differences between the lakes. Total phosphorus (TP) concentrations, and not light, were expected to limit productivity. Significant differences in these lakes were found based on morphological differences, with larger lakes demonstrating lower chlorophyll a concentrations. TP concentrations were found to limit productivity. TSI values were mainly consistent with past values measured for these lakes