Updated Aug 2026
Pennsylvania Lake Water Quality
Water quality grades for 4 monitored lakes across 4 counties.
4 Pennsylvania lakes carry a grade. Most of the input data flows through monitoring run by the Pennsylvania Department of Environmental Protection, which feeds state, federal, and volunteer measurements into the EPA Water Quality Portal. A-grade lakes are scarce in Pennsylvania: about 0% of the dataset. Most lakes here sit in C or D — productive, often shallow, frequently algal in late summer.
The state's dominant trophic class is oligotrophic: clear, nutrient-poor, slow-growing. These lakes are also the most sensitive to disturbance — the same volume that buffers them against nutrients also slows recovery if those nutrients arrive in quantity. a leading county ranks highest on average county grade (—). a struggling county sits lowest. With only 4 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 4 Pennsylvania lakes in the index: 0 (0.0%) carry an A–F grade and 4 (100.0%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Where to stay near Pennsylvania
Top-rated places to stay near Pennsylvania
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Lake Map
Explore Pennsylvania Lakes
Pennsylvania reports, fishing & travel
Reservoirs in Pennsylvania
View all 2 reservoirs →2 of 4 Pennsylvania lakes (50%) 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 4 Pennsylvania lakes (75%) 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 4 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.
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
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
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.