Jacksonville Lake vs Otter Lake
Water quality, depth, fish species, and recreation comparison.
Jacksonville Lake and Otter Lake both received the same overall water quality grade of F (Algae-prone). Both are in Illinois.
Both Jacksonville Lake and Otter 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. These two are within a letter of each other on the rubric — Jacksonville Lake (F) versus Otter Lake (F). The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
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.
Jacksonville Lake
Very murky, less than 1.8 ft of visibility.
Otter Lake
Very murky, less than 1.8 ft of visibility.
Side-by-Side Metrics
| Metric | Jacksonville Lake | Otter Lake |
|---|---|---|
| Overall Grade | F (Algae-prone) | F (Algae-prone) |
| Water Clarity | 1.8 ft | 1.8 ft |
| Phosphorus | 60.5 µg/L Better | 81 µg/L |
| Chlorophyll-a (Algae) | 42.2 µg/L | 33.1 µg/L Better |
| Maximum Depth | - | - |
| Surface Area | 477 acres | 760 acres |
| Public Access | Yes | Yes |
| Fish Species | 0 | 0 |
| Trophic State | hypereutrophic | hypereutrophic |
A green ✓ marks the better value for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better). Surface area and trophic state carry no tick — a bigger lake is not a better lake.
Swap a lake
Compare Jacksonville Lake or Otter Lake against a different lake.
Verdict
Both lakes earn the same Grade F. The tiebreakers come down to clarity (Jacksonville Lake: 1.8 ft, Otter Lake: 1.8 ft) and what you want from the lake. Jacksonville Lake matches its peer on species count.
Source: EPA National Aquatic Resource Surveys, 2026.