Phosphorus is essential to the growth of biological organisms, including both their metabolic and photosynthetic processes. Phosphorus occurs naturally in bodies of water mainly in the form of phosphate (i.e., a compound of phosphorus and oxygen). Addition of phosphates through the activities of humans can accelerate the eutrophication process of nutrient enrichment that results in accelerated ecological aging of lakes and streams. Phosphorus, especially in inland waters, is often the nutrient that limits growth of aquatic plants. Thus when it is added to a body of water, it may result in increased plant growth that gradually fills in the lake. Critical levels of phosphorus in water, above which eutrophication is likely to be triggered, are approximately 0.03 mg/l of dissolved phosphorus and 0.1 mg/l of total phosphorus. The discharge of raw or treated wastewater, agricultural drainage, or certain industrial wastes that contain phosphates to a surface water...