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Surface Water Quality

Wisconsin is a state rich with surface water, including lakes, streams, wetlands, aquifers and springs. Wisconsin has thousands of streams stretching over 84,000 miles, more than one million acres of inland lakes, 1,000 miles of Great Lakes shoreline and more than five million wetland acres. Learn how the DNR protects and restores these surface waters through water quality monitoring, water quality standards and more.

50 Years of Clean Water Act

Since 1972, this federal law has guided Wisconsin’s efforts to protect and enhance our state’s water resources.

Wisconsin's 2024 Water Quality Report to Congress

The 2024 report was created based on water quality monitoring and restoration work done from 2021-2022.

Monitoring Wisconsin Waters

The DNR monitors aquatic resources to assess ecosystem health and evaluate environmental problems.


The Clean Water Act (CWA) requires states to assess the quality of its surface waters and report results to the public.