Birch Lake vs Boulder Lake
Water quality, depth, fish species, and recreation comparison.
Birch Lake and Boulder Lake both received the same overall water quality grade of B (Good). Both are in Vilas County, Wisconsin.
Birch Lake and Boulder Lake 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. These two are within a letter of each other on the rubric — Birch Lake (B) versus Boulder Lake (B). The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
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.
Birch Lake
Murky, only visible to about 6.5 ft.
Boulder Lake
Murky, only visible to about 5.6 ft.
Side-by-Side Metrics
| Metric | Birch Lake | Boulder Lake |
|---|---|---|
| Overall Grade | B (Good) | B (Good) |
| Water Clarity | 6.5 ft | 5.6 ft |
| Phosphorus | 16.3 µg/L | 21.6 µg/L |
| Chlorophyll-a (Algae) | No data | No data |
| Maximum Depth | 45 ft | 23 ft |
| Surface Area | 506 acres | 516 acres |
| Public Access | Yes | Yes |
| Fish Species | 6 | 6 |
| Trophic State | mesotrophic | eutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Both lakes earn the same Grade B. The tiebreakers come down to clarity (Birch Lake: 6.5 ft, Boulder Lake: 5.6 ft) and what you want from the lake. Birch Lake matches its peer on species count.
Source: EPA National Aquatic Resource Surveys, 2026.