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LakeQuality
F

Decatur County Lake Quality

Indiana, 1 lakes, average grade F (Very Poor)

Decatur 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. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.

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. a leading lake (—) is the cleanest in the county.

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All Lakes in Decatur County

RankLakeGradeClarityPhosphorus

Source: EPA National Aquatic Resource Surveys, 2026.