Phosphorus is one of the nutrients essential for life in all organisms. It is used in fundamental life processes such as storage and transfer of genetic information, cell metabolism, and in the energy systems of cells. In lakes, phosphorus is usually present in small amounts, but usually increases with the amount of human impact on the land surrounding the lake. Phosphorus is almost always a limiting nutrient to plant growth in a lake, meaning that plant growth increases at the same rate as phosphorus is added to the system.

Phosphorus can enter a lake from the land surrounding the water body by way of sediments, lawn/garden fertilizer, by septic waste washing into the lake or by way of streams that carry and deposit pollutants the lake.

Resources:
Bronmark, Christer and Lars-Anders Hansson. 1998. The Biology of Lakes and Ponds. New York. Oxford University Press.

Kalff, Jacob. 2002. Limnology. Upper Saddle River, N.J. Prentice Hall.