Fig. 6. Relationship between water quality data and modified P Index rating for selected watersheds of Minnesota. (a) Relationship between modified P Index rating and percentage of samples exceeding 0.25 mg/L total P for watersheds within the Upper Mississippi River, Lower Mississippi River, Minnesota River, St. Croix River, and Cedar River Basins. (b) Relationship between modified P Index rating and median total P concentrations of lakes. (c) Relationship between modified P Index rating and percentage of samples exceeding 0.25 mg/L total P for watersheds within the Red River Basin.
