Water Quality


Maine's water quality far exceeds the national average but no new data has been released since 2016

No significant movement since the last available data

Benchmark: The percentage of Maine’s assessed water bodies classified as Categories 1 or 2 will be maintained over time.

Overview Fig. A


This measure is based on reports by the Maine Department of Environmental Protection (MDEP) and U.S. Environmental Protection Agency (EPA) on the water quality of Maine rivers, streams, and lakes. The proportion of water bodies achieving Maine’s Category 1 and 2 classifications are compared with U.S. water bodies receiving the EPA’s “good” classification. Maine’s rivers, lakes, and streams provide drinking water and support ecosystems. They are part of the natural environment that supports tourism.

Since 2006, Maine’s water quality has remained steady, with 95% of rivers and streams and 91% of lakes achieving Category 1 or 2 in 2016. Nationally, about 47% of U.S. rivers and streams and 29% of the lakes were rated “good.” MDEP expects to release 2018 and 2020 data for this measure in 2022.

Fig. A

On mobile? Viewing this data is easier at a computer.

Water Bodies Rated Category 1 or 2 ("Good")

Maine Department of Environmental Protection