Delavan Lake vs Lake Beulah
Water quality, depth, fish species, and recreation comparison.
Lake Beulah has a higher water quality grade (A, Excellent) than Delavan Lake (C, Fair). Both are in Walworth County, Wisconsin.
Both Delavan Lake and Lake Beulah sit in Wisconsin. 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 meaningfully apart: Lake Beulah grades a A while Delavan Lake grades a C. 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 — Lake Beulah 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?
Delavan Lake
Moderate clarity, visible to about 8.9 ft.
Lake Beulah
Good clarity, visible to about 10 ft.
Side-by-Side Metrics
| Metric | Delavan Lake | Lake Beulah |
|---|---|---|
| Overall Grade | C (Fair) | A (Excellent) |
| Water Clarity | 8.9 ft | 10 ft |
| Phosphorus | 52.5 µg/L | 13.4 µg/L |
| Chlorophyll-a (Algae) | 9.1 µg/L | 2.5 µg/L |
| Maximum Depth | 52 ft | 58 ft |
| Surface Area | 1,906 acres | 812 acres |
| Public Access | Yes | Yes |
| Fish Species | 6 | 3 |
| Trophic State | eutrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Lake Beulah wins on overall water quality with a Grade A versus Delavan Lake's Grade C. Water clarity: 10 ft vs 8.9 ft. For more fish-species variety, Delavan Lake edges ahead with 6 documented species.
Source: EPA National Aquatic Resource Surveys, 2026.