Wisconsin’s Phosphorus Rule is Approved

In December, 2010 Wisconsin became the first state in the country to adopt phosphorus water quality standards for lakes, reservoirs, rivers, and streams.  The Environmental Protection Agency has approved Wisconsin’s revised rule as a revision to Wisconsin’s federally-approved National Pollutant Discharge Elimination System program under the Clean Water Act.

Under the new rules DNR determines the phosphorus discharge limits based on the condition and quality of a watershed.  Limits can vary depending on whether a waterway is already impaired by phosphorus, among other factors.

Already this summer, many Wisconsin lakes are experiencing algae blooms and excessive aquatic plant growth, both of which are fueled by phosphorus pollution.  The excess nutrients increase the populations of algae, which can multiply in waterways particularly when the water is warm and the weather is calm. 

Algae is typically not harmful to humans, however, some species produce toxins which can affect people by causing illness so swimming and other water activities should be avoided in areas where algal is present.  Blue-green algae blooms have been blamed for the deaths of many dogs which are more vulnerable because they often drink the contaminated water or swallow the algae as they clean their coats. 

Almost 175 Wisconsin waters are officially listed as “impaired” due to excessive phosphorus levels.  The new rules will help clean up those lakes and protect the others.  The new rule is in addition to a smaller effort from 2009 which restricted the sale of fertilizers containing phosphorus and banned the sale of dishwasher detergents with phosphorus.