Skip to main content
LakeQuality

Lake Water Quality Answers

Direct answers to the questions people most often ask about Minnesota and Wisconsin lakes. Each answer pulls from EPA water quality data, Metropolitan Council grading methodology, and DNR fish surveys. Drill into a specific lake, a state, a county, or a general topic.

By State

Cleanest Lakes by County

Top 32 highest-lake-count counties shown. See all 144 counties →

Topics & Definitions

Lake-Specific Answers

Every 1,000 answerable lake has three dedicated Q&A pages: swim safety, cleanliness, and (where data exists) fish species. Featured lakes below — search the full set on any lake page or the search page.

Rainy Lake
Koochiching County, Minnesota
Rainy Lake
St. Louis County, Minnesota
Rainy Lake
St. Louis County, Minnesota
Rainy Lake
St. Louis County, Minnesota
Rainy Lake
Koochiching County, Minnesota
Rainy Lake
Koochiching County, Minnesota
Rainy Lake
Koochiching County, Minnesota
Rainy Lake
Koochiching County, Minnesota
Rainy Lake
Koochiching County, Minnesota
Mille Lacs Lake
Aitkin County, Minnesota
Mille Lacs Lake
Mille Lacs County, Minnesota
Ml-Nw Lake
Aitkin County, Minnesota
Ml-Ditch 36 Lake
Aitkin County, Minnesota
Ml-Thains Lake
Mille Lacs County, Minnesota
Ml-Ce Lake
Aitkin County, Minnesota
Ml-Seventeen Lake
Aitkin County, Minnesota
Ml Lake
Mille Lacs County, Minnesota
Ml Lake
Mille Lacs County, Minnesota
Ml-Se Lake
Mille Lacs County, Minnesota
Ml-Vineland Lake
Mille Lacs County, Minnesota
Ml-Peterson Lake
Mille Lacs County, Minnesota
Ml-Malone Lake
Mille Lacs County, Minnesota
Ml-Garrison Lake
Aitkin County, Minnesota
Ml-Nshore Lake
Aitkin County, Minnesota