Skip to main content
LakeQuality

Data Report · Updated July 2026

The State of Pennsylvania’s Lakes 2026

Of 3 monitored lakes in Pennsylvania, 0% earn a water-quality grade of A or B and 100% score D or F (average grade D). 3 lakes (100%) are on an official impaired-waters list.

3
Monitored lakes graded
D
Average grade
0%
Grade A or B
100%
On impaired list

Pennsylvania grade distribution

D
A: 0 (0.0%)B: 0 (0.0%)C: 0 (0.0%)D: 3 (100.0%)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. 1.DLake 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

Grades combine Secchi clarity, total phosphorus, and chlorophyll-a 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,” lakequality.org/report/pa.