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LakeQuality

Decatur Lake vs Lake Springfield

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

Decatur Lake and Lake Springfield both received the same overall water quality grade of F (Very Poor). Both are in Wisconsin.

Decatur Lake and Lake Springfield 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: Decatur Lake (F) and Lake Springfield (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.

F

Decatur Lake

Macon County, Wisconsin

Very murky, less than 1.3 ft of visibility.

F

Lake Springfield

Sangamon County, Wisconsin

Very murky, less than 1.5 ft of visibility.

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.

MetricDecatur LakeLake Springfield
Overall GradeF (Very Poor)F (Very Poor)
Water Clarity1.3 ft1.5 ft
Phosphorus90 µg/LNo data
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area3.3K acres4.2K acres
Public AccessUnknownUnknown
Fish Species00
Trophic Statehypereutrophichypereutrophic

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, Lake Springfield: 1.5 ft) and what you want from the lake. Decatur Lake matches its peer on species count.