Decatur Lake vs Mattoon Lake
Water quality, depth, fish species, and recreation comparison.
Decatur Lake and Mattoon Lake both received the same overall water quality grade of F (Very Poor). Both are in Wisconsin.
Both Decatur Lake and Mattoon Lake sit in Illinois. A same-state comparison strips out the state-level water-quality regime as a variable: any grade differences here are about the lakes themselves, not the agencies grading them. The grades are close: Decatur Lake (F) and Mattoon Lake (F) are within one letter of each other on the LakeGrade rubric. The per-parameter sub-grades below will show where the small differences actually live.
With grades this close, the choice between the two lakes turns on non-water-quality factors: depth, fish species, public access, distance from home. The per-lake pages below cover all of those.
Decatur Lake
Very murky, less than 1.3 ft of visibility.
Mattoon Lake
Very murky, less than 1.3 ft of visibility.
Side-by-Side Metrics
| Metric | Decatur Lake | Mattoon Lake |
|---|---|---|
| Overall Grade | F (Very Poor) | F (Very Poor) |
| Water Clarity | 1.3 ft | 1.3 ft |
| Phosphorus | 90 µg/L | 206 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | - | - |
| Surface Area | 3.3K acres | 980 acres |
| Public Access | Unknown | Unknown |
| Fish Species | 0 | 0 |
| Trophic State | hypereutrophic | hypereutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Both lakes earn the same Grade F. The tiebreakers come down to clarity (Decatur Lake: 1.3 ft, Mattoon Lake: 1.3 ft) and what you want from the lake. Decatur Lake matches its peer on species count.