The National Lakes Assessment (NLA) is a statistical survey of the condition of our nation's lakes, ponds, and reservoirs. It is designed to provide information on the extent of lakes that support healthy biological conditions and recreation, estimate how widespread major stressors are that impact lake quality, and provide insight into whether lakes nationwide are getting cleaner.

The most recent survey of 50 Minnesota lakes through the NLA found that all of them contained at least one chemical contaminant. The researchers tested for 163 chemicals, including pharmaceuticals, the pesticide DEET, alkylphenols, hormones, illicit drugs, anti-corrosive chemicals, and disinfectants. Of the 163 chemicals tested:

  • 55 were found in lakes at least once
  • 21 of these chemicals may pose a risk to aquatic ecosystems

This and several previous investigations of varying size over the past 10 years clearly demonstrate that these “contaminants of emerging concern” are widespread in our lakes, rivers, and streams. Many of these chemicals are endocrine active, mimicking naturally occurring hormones. Concern is growing over the effect these chemicals may have on fish and wildlife and human health at very low concentration.

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