Union County Lake Quality
Iowa, 6 lakes, measured by Iowa DNR
Union County holds 6 monitored lakes. 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 lakes carries recent nutrient and algae readings, so the county-level summary covers the full set rather than a monitored subset. The monitored lakes here are mostly shallow, productive basins where summer algae is common; each lake page shows its own readings beside the EPA condition class.
The county's lakes lean shallow, which makes the readings sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest measured lake is Three Mile Lake.
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Quick Answers for Union County
Planning a trip? Check special fishing regulations for Three Mile Lake — or check the official Iowa fishing regulations.
All Lakes in Union County
6 lakes6 lakes ranked on readings
| # | Lake | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | Three Mile LakeUnion | 2.7 ft | 43 µg/L | 28.4 µg/L | No recent samples | ✓ Public |
| 2 | Twelve Mile LakeUnion | 2.4 ft | 79 µg/L | 45 µg/L | No recent samples | ✓ Public |
| 3 | Green Valley LakeUnion | 1.5 ft | 103 µg/L | 61.7 µg/L | No recent samples | ✓ Public |
| 4 | Summit LakeUnion | 1.4 ft | 121 µg/L | 45.7 µg/L | No recent samples | ✓ Public |
| 5 | Mckinley LakeUnion | 1 ft | 150 µg/L | 69.3 µg/L | No recent samples | Not recorded |
| 6 | Thayer LakeUnion | 3.5 ft | 68 µg/L | 34.3 µg/L | No recent samples | Not recorded |
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Source: the Iowa Department of Natural Resources. See data sources.