An essential nutrient for animals and plants, it is a common ingredient in fertilizers, and human sewage is a rich source of phosphorus. Phosphorus clings to soil and is carried or exported from forests and fields into lakes and streams by water from rainstorms and snow melt.
Export can also occur when land is developed or paved.
Paved surfaces also allow water from storms and other sources to move very quickly and wash into streams and lakes along with other phosphorus-containing pollutants such as motor oils and fuels. Phosphorus is an element essential to plant life and is present in most fertilizers. But what makes your lawn and garden green can also make your lake green by promoting an overgrowth of algae and weeds. Each season, algae and weeds die, fall to the lakes bottom and decay. The decay process deprives water of oxygen and causes fish and other aquatic life to die.