Boulder Lake vs Plum Lake
Water quality, depth, fish species, and recreation comparison.
Boulder Lake and Plum Lake read the same on nutrients and algae. Both are in Vilas County, Wisconsin.
Both Boulder Lake and Plum Lake sit in Wisconsin. A same-state comparison strips out the state-level water-quality regime as a variable: any differences in the readings here are about the lakes themselves, not the agencies sampling them. The readings are close: Boulder Lake and Plum Lake sit within a narrow band of each other on phosphorus, chlorophyll-a and clarity. The per-parameter table below shows where the small differences actually live.
With readings 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.
Boulder Lake
Murky, only visible to about 5.6 ft.
Plum Lake
Good clarity, visible to about 14.2 ft.
Side-by-Side Metrics
| Metric | Boulder Lake | Plum Lake |
|---|---|---|
| Water Clarity | 5.6 ft | 14.2 ft Better |
| Phosphorus | 21.6 µg/L | 13 µg/L Better |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | 23 ft | 57 ft Better |
| Surface Area | 516 acres | 1,057 acres |
| Public Access | Yes | Yes |
| Fish Species | 6 | 6 |
| Trophic State | eutrophic | oligotrophic |
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 Boulder Lake or Plum Lake against a different lake.
Verdict
Both lakes earn the same Grade B. The tiebreakers come down to clarity (Boulder Lake: 5.6 ft, Plum Lake: 14.2 ft) and what you want from the lake. Boulder Lake matches its peer on species count.
Source: EPA National Aquatic Resource Surveys, 2026.