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LakeQuality
C

Perry County Lake Quality

Illinois, 2 lakes, average grade C (Fair)

Only 2 lakes in Perry County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.

Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Boulder South Lake (B) is the cleanest in the county.

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All Lakes in Perry County

RankLakeGradeClarityPhosphorus
1Boulder South LakeB8.8 ft14.5 µg/L
2Wesslyn Cut LakeD4.5 ft109 µg/L

See how Perry County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 15 states.

Where to stay near Perry County

Top-rated places to stay near Perry County

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Source: EPA National Aquatic Resource Surveys, 2026.