
Madison County Lake Quality
Illinois, 10 lakes, measured by Illinois EPA
Madison 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. 2 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.
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. Holiday Shores Lake has the lowest nutrient and algae readings in the county.
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Quick Answers for Madison County
Planning a trip? Check special fishing regulations for Holiday Shores Lake — or check the official Illinois fishing regulations.
All Lakes in Madison County
10 lakes · 2 ranked on readings, 8 without enough sampling2 lakes ranked on readings · 8 without enough sampling, hidden
| # | Lake | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|
| 1 | Holiday Shores LakeMadison | 1.7 ft | 136.5 µg/L | 32.1 µg/L | No recent samples | No recent samples | Not recorded |
| 2 | Highland Silver LakeMadison | 1.3 ft | 123 µg/L | 57.3 µg/L | No recent samples | No recent samples | ✓ Public |
| Highland Silver LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | 25 ft | Not recorded | |
| Dunlap LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | 27 ft | Not recorded | |
| McDonough LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| Tower LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | 30 ft | Not recorded | |
| Long LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| Long LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| Canteen LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| Horseshoe LakeMadison | No recent samples | No recent samples | No recent samples | No recent samples | 6 ft | ✓ Public |
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.