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LakeQuality

Delavan Lake vs Outlet To Lake Geneva

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

Delavan Lake has a higher water quality grade (B, Good) than Outlet To Lake Geneva (D, Poor). Both are in Walworth County, Wisconsin.

Reviewed by LakeQuality Editorial Team · Updated

Delavan Lake and Outlet To Lake Geneva are both in Wisconsin — 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 meaningfully apart: Delavan Lake grades a B while Outlet To Lake Geneva grades a D. That two-letter spread reflects real underlying differences — different watershed inputs, different depth profiles, or different monitoring rigor.

For a recreational visitor, the wider grade gap is decisive — Delavan Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?

B

Delavan Lake

Walworth County, Wisconsin

No clarity data.

D

Outlet To Lake Geneva

Walworth County, Wisconsin

No clarity data.

Side-by-Side Metrics

MetricDelavan LakeOutlet To Lake Geneva
Overall GradeB (Good)D (Poor)
Water ClarityNo dataNo data
Phosphorus25.9 µg/L658 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth52 ft135 ft
Surface Area1,906 acres5,401 acres
Public AccessYesYes
Fish Species66
Trophic Stateeutrophichypereutrophic

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

Verdict

Delavan Lake wins on overall water quality with a Grade B versus Outlet To Lake Geneva's Grade D. For fishing diversity, Delavan Lake also leads with 6 species.

Source: EPA National Aquatic Resource Surveys, 2026.