Phosphorus is a limiting plant nutrient and increases in phosphorus can result in algal blooms, which decrease bottom dissolved oxygen concentrations and water clarity.
	In unpolluted lakes, most of the phosphorus is found in bottom sediments, tied up in aluminum, iron, and calcium complexes. The release of phosphorus into the water by these complexes depends upon pH and bottom dissolved oxygen levels. When waters become anoxic and dissolved oxygen levels drop below 1 ppm, phosphate complexes are reduced and phosphorus is released into the water. Once released, the phosphorus can affect the entire water column through turnover.