What does Phosphorus Do to a Lake?
Nitrogen, potash, and phosphorus are the nutrients necessary for plant growth.
Phosphorus is the key nutrient needed for aquatic plant and algae growth. When excessive
phosphorus reaches the lake, it fuels the overgrowth of aquatic plants and algae, those microscopic organisms that give water a greenish tinge and can cause blue-green,
toxic scums along the shore. Excessive plant and algae growth decreases water clarity,
interferes with the recreational use of the lake, and diminishes oxygen for fish in the
water, generally causing declining water quality.
Natural rainfall contains high amounts of phosphorus, which we can’t control, but we can
control our own shoreland practices that can contribute phosphorous to the lake.
Excessive phosphorus can get into lakes from shoreland properties in a number of
• excessive application to and runoff from lawns;
• decomposition of leaves and other plant material;
• erosion of soil, which has phosphorus particles attached to it;
• improper human and pet waste management, both of which contain high amounts of phosphorus; and the
• use of household products high in phosphorus.