Updated Aug 2026
Maine Lake Water Quality
1,527 lakes across 16 counties, 18 with a recent water-quality reading.
Lake Map
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New water-quality readings for Maine lakes as Maine DEP publishes them. Unsubscribe anytime.
Where to stay near Maine's cleanest lakes
Cabins, resorts, and vacation rentals around Big Lake (Washington County, ME) and the other cleanest Maine lakes pinned on the map. Live availability and prices.
Top-rated places to stay near Big Lake (Washington County, ME)
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Maine fishing & travel
Reservoirs in Maine
View all 5 reservoirs →5 of 1,527 Maine lakes (0%) are man-made reservoirs in the USACE National Inventory of Dams. 3 carry a High or Significant hazard rating. The oldest matched dam dates to 1836.
EPA-Impaired Lakes in Maine
View all 21 impaired lakes →21 of 1,527 Maine lakes (1%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 13 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Maine Fishing & Recreation
Licenses, regulations, records, and where to fish across Maine.
Counties
All 16 Maine counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of lakes, or pick a different state.
18 of the 1,527 Maine lakes in this index carry a recent clarity, phosphorus or algae reading, spread over 16 counties. Those readings come from the Maine Department of Environmental Protection, alongside federal programs and volunteer monitoring networks. The rest are listed for their size, depth and location, with no recent nutrient or algae sampling behind them.
By surface area the largest lake here is Moosehead Lake, at about 75,598 acres, and 293 of the lakes in this index cover more than 500 acres. Size is worth knowing before you go: a large deep basin buffers nutrient inputs by sheer volume, while a shallow one warms quickly and can turn over its whole water column in a single summer storm. Hancock has the lowest nutrient and algae readings on average. With only 16 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
A data snapshot of the lakes we track: the clearest and the greenest states, and where the water is improving.
How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.
The clearest lakes in America, ranked by measured Secchi depth in feet from EPA monitoring data — and why the famously clear lakes are missing.