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LakeQuality
Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water
F

Monroe County Lake Quality

Iowa, 1 lake, average grade F (Algae-prone)

Monroe County holds 1 monitored lake. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. Every one of those lake carries an A–F grade, so the county-level summary covers the full set rather than a monitored subset. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.

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 Miami Max Depth (F); the most-stressed is Lake Miami Max Depth (F).

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All Lakes in Monroe County

1 lake1 graded lake

#LakeGradeClarityPhosphorusAlgaeTrophicAccess
1FLake Miami Max DepthMonroeF1.3 ft132.5 µg/L58.6 µg/LNo recent samples✓ Public

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See how Monroe County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: EPA National Aquatic Resource Surveys, 2026.