Updated August 2026
The State of Pennsylvania's Lakes 2026
Of 4 lakes in Pennsylvania, 0% earn a water-quality grade of A or B and 0% score D or F (average grade F). 3 lakes (75%) are on an official impaired-waters list.
Data Report
4
Monitored lakes graded
F
Average grade
0%
Grade A or B
75%
On impaired list
Pennsylvania grade distribution
A: 0 (0.0%)B: 0 (0.0%)C: 0 (0.0%)D: 0 (0.0%)F: 0 (0.0%)
Cleanest lakes in Pennsylvania
Highest combined water-quality score, 2026.
No qualifying lakes with sufficient data.
Most-polluted lakes
Lowest combined water-quality score among monitored lakes.
No qualifying lakes with sufficient data.
Worst algae hotspots
Highest measured chlorophyll-a (algae) concentration.
No qualifying lakes with sufficient data.
Trending lakes
Improving
- 1.NRLake Wallenpaupack — Pike County
Impaired waters in Pennsylvania
3 lakes appear on the EPA/state 303(d) impaired-waters list (1 formally listed, 3 with a cleanup plan/TMDL).
Nutrients (phosphorus, nitrogen) · 2Mercury · 1Turbidity · 1
Explore Pennsylvania lakes
Grades combine total phosphorus, total nitrogen, chlorophyll-a, and turbidity from the EPA Water Quality Portal and state agencies. See the full methodology, the national State of America’s Lakes report, or all Pennsylvania lakes.
Cite this report: LakeQuality, “The State of Pennsylvania's Lakes 2026”.