Updated Jul 2026
Pennsylvania Lake Water Quality
Water quality grades for 3 monitored lakes across 8 counties.
3 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 lakes lean eutrophic: enough nutrient input to support an active algal community, with the trade-offs in clarity and dissolved oxygen that come with it. Erie ranks highest on average county grade (A). Pike sits lowest. With only 8 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
How Pennsylvania’s 3 graded lakes break down from A (excellent) to F.
Top-Graded Pennsylvania Lakes
The highest water-quality grades in Pennsylvania — clarity, depth, and A-F grade at a glance.
Lake Map
Explore Pennsylvania Lakes
Pennsylvania reports, fishing & travel
Reservoirs in Pennsylvania
View all 2 reservoirs →2 of 3 Pennsylvania lakes (67%) 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 3 Pennsylvania lakes (100%) 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 8 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.
Top 25 Cleanest Lakes
| Rank | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | Lake Wallenpaupack | Pike | D | 5.7 ft |
| 2 | Lake Carey | Wyoming | D | 5.9 ft |
| 3 | Lake Nockamixon | Bucks | D | 4.8 ft |
25 Lakes Needing Attention
| Rank | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | Lake Nockamixon | Bucks | D | 4.8 ft |
| 2 | Lake Carey | Wyoming | D | 5.9 ft |
| 3 | Lake Wallenpaupack | Pike | D | 5.7 ft |
Where to stay near Pennsylvania
Top-rated places to stay near Pennsylvania
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Source: EPA National Aquatic Resource Surveys, 2026.