A lake with high water quality has the necessary amount of dissolved oxygen in the water to sustain life:
Phosphorus, whether from surface runoff or from other sources, disrupts the balance related to oxygen supply.
A nutrient, phosphorus accelerates the growth of algae, sometimes creating unsightly algal blooms. When these algae die, their decomposition can deplete the dissolved oxygen supply necessary to support fish and other aquatic life. This affects water clarity, and, in general, upsets the food web.
Phosphorus is only one of many pollutants that may affect water quality. Sediment, bacteria, pesticides, toxins, and many other substances can negatively alter a lake's ecosystem through impacts on aquatic life, water chemistry, and physical conditions. We can reduce the amount of pollutants that reach a lake by conscientious decisions on how we use both the land and the water.
For more information, refer to the Minnesota Shoreland Management Resource Guide . Designed for citizen use, the Shoreland Guide offers information and links on water quality, lake and river management, and many other topics.