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LakeQuality

Jacksonville Lake vs Mauvaise Terre Lake

Water quality, depth, fish species, and recreation comparison.

Jacksonville Lake has a higher water quality grade (D, Poor) than Mauvaise Terre Lake (F, Very Poor). Both are in Morgan County, Wisconsin.

Jacksonville Lake and Mauvaise Terre Lake are both in Illinois — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. The grades are close: Jacksonville Lake (D) and Mauvaise Terre 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.

D

Jacksonville Lake

Morgan County, Wisconsin

Very murky, less than 1.8 ft of visibility.

F

Mauvaise Terre Lake

Morgan County, Wisconsin

No clarity data.

Side-by-Side Metrics

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

MetricJacksonville LakeMauvaise Terre Lake
Overall GradeD (Poor)F (Very Poor)
Water Clarity1.8 ftNo data
Phosphorus48 µg/L162 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area477 acres262 acres
Public AccessUnknownUnknown
Fish Species00
Trophic Stateeutrophichypereutrophic

Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).

Verdict

Jacksonville Lake wins on overall water quality with a Grade D versus Mauvaise Terre Lake's Grade F. For fishing diversity, Jacksonville Lake also leads with 0 species.