Phosphorus is not just found in fertilizer— it is contained in almost any organic material such as leaves, grass clippings, pet waste, and cleaners like car- and dish-washing soap. Even an unfertilized lawn contributes excess nutrients, including phosphorus, to the lake. Lawns, fertilized or not, generate more phosphorus per year than forested or landscaped areas. When those lawns discharge runoff into ditches, pipes, creeks, and shallow groundwater, more phosphorus ends up in the Lake. While grass is a great filter for pollutants like metals and oils, it is both a source and poor filter for nutrients like phosphorus.