Updated Aug 2026
Pennsylvania Lake Water Quality
570 lakes across 65 counties, 3 with a recent water-quality reading. None carries an A–F grade.
Grade Distribution
All 570 Pennsylvania lakes in the index: 0 (0.0%) carry an A–F grade and 570 (100.0%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Lake Map
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New grades, clarity readings, and algae advisories for Pennsylvania lakes as samples come in. Unsubscribe anytime.
Where to stay near Pennsylvania's top-graded lakes
Cabins, resorts, and vacation rentals around Belmont Lake (Wayne County, PA) and the other top-graded Pennsylvania lakes pinned on the map. Live availability and prices.
Top-rated places to stay near Belmont Lake (Wayne County, PA)
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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Explore Pennsylvania Lakes
Pennsylvania reports, fishing & travel
Pennsylvania's cleanest and most-polluted lakes, ranked A–F
Species activity outlook by water temperature and season
Where to stay at Pennsylvania's top lakes, each with its grade
Best-graded lakes within 50 miles of Pittsburgh
Best-graded lakes within 50 miles of Erie
Reservoirs in Pennsylvania
View all 2 reservoirs →2 of 570 Pennsylvania lakes (0%) are man-made reservoirs in the USACE National Inventory of Dams. 2 carry a High or Significant hazard rating. The oldest matched dam dates to 1876.
EPA-Impaired Lakes in Pennsylvania
View all 3 impaired lakes →3 of 570 Pennsylvania lakes (1%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 3 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Pennsylvania Fishing & Recreation
Licenses, regulations, records, and where to fish across Pennsylvania.
Counties
All 65 Pennsylvania counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
Pennsylvania Lake Water Quality Dataset (2026)
Every graded Pennsylvania lake in one spreadsheet — A–F grade, water clarity, phosphorus, chlorophyll-a, trophic state, size, public access, and a link to each lake's report card.
Pennsylvania lists 570 lakes across 65 counties, 3 of them with a recent clarity, phosphorus or algae reading. That is not enough sampling anywhere in the state to support an A–F letter, so none of these lakes carries one. The rest are here because they are real named lakes, listed for their size, depth and location.
Pymatuning Reservoir is the largest lake in this index at about 13,926 acres, one of 30 here that clear 500 acres. The rest run smaller, and small and shallow is where nutrient loading shows up first, because there is less water to dilute it and the bottom sediment stays within reach of the sun.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded 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 grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.
The cleanest and dirtiest U.S. lakes in the monitoring record, ranked on EPA nutrient and algae condition classes across thousands of graded lakes.
The clearest lakes in America, ranked by measured Secchi depth in feet from EPA monitoring data — and why the famously clear lakes are missing.