Marion County Lake Quality
Illinois, 10 lakes, measured by Illinois EPA
Marion County has 10 monitored 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. 6 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. 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 Salem Lake.
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Quick Answers for Marion County
Planning a trip? Check special fishing regulations for Salem Lake — or check the official Illinois fishing regulations.
All Lakes in Marion County
10 lakes · 6 ranked on readings, 4 without enough sampling6 lakes ranked on readings · 4 without enough sampling, hidden
| # | Lake | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|
| 1 | Salem LakeMarion | 1 ft | 234 µg/L | 77.5 µg/L | No recent samples | No recent samples | ✓ Public |
| 2 | Forbes LakeMarion | 1.4 ft | 140.5 µg/L | 75.9 µg/L | No recent samples | No recent samples | ✓ Public |
| 3 | Centralia LakeMarion | 1.5 ft | 132 µg/L | 69.7 µg/L | No recent samples | No recent samples | ✓ Public |
| 4 | Raccoon LakeMarion | 1.2 ft | 285 µg/L | 73.5 µg/L | No recent samples | No recent samples | ✓ Public |
| 5 | Kinmundy Old LakeMarion | 1.5 ft | 277 µg/L | 114.8 µg/L | No recent samples | No recent samples | Not recorded |
| 6 | Kinmundy New LakeMarion | 2.9 ft | 49.5 µg/L | 38 µg/L | No recent samples | No recent samples | ✓ Public |
| Lake CentraliaMarion | No recent samples | No recent samples | No recent samples | No recent samples | 25 ft | Not recorded | |
| Forbes LakeMarion | No recent samples | No recent samples | No recent samples | No recent samples | 28 ft | ✓ Public | |
| Salem ReservoirMarion | No recent samples | No recent samples | No recent samples | No recent samples | 14 ft | Not recorded | |
| C and EI ReservoirMarion | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded |
NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.
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Source: the Illinois Environmental Protection Agency. See data sources.