A total of 1,028 lakes were randomly sampled during 2007 by states, tribes and the EPA. The National Lakes Assessment survey included a comparison to a subset of lakes with wastewater impacts which were sampled in the 1970s. The survey finds that 75% of the lakes show either improvements or no change in phosphorus levels, suggesting that the nation’s investments in wastewater treatment and other pollution control activities are working despite population increases across the country.

Peter Silva, assistant administrator for EPA’s Office of Water said: “This survey serves as a first step in evaluating the success of efforts to protect, preserve and restore the quality of our nation’s lakes. Future surveys will be able to track changes in lake water quality over time and advance our understanding of important regional and national patterns in lake water quality.”
 

Sampling for the National Rivers and Streams Assessment is underway, and results from this two-year study are expected to be available in 2011.