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LakeQuality
C

Williamson County Lake Quality

Wisconsin, 1 lakes, average grade C (Fair)

Williamson County has 1 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. Williamson County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.

The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Lake of Egypt (C); the most-stressed is Lake of Egypt (C).

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All Lakes in Williamson County

RankLakeGradeClarityMax DepthPhosphorus
1Lake of EgyptC3.2 ft-26 µg/L

Source: EPA National Aquatic Resource Surveys, 2026.