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Boulder Lake and Kentuck Lake read the same on nutrients and algae. Both are in Vilas County, Wisconsin.

Reviewed by LakeQuality Editorial Team · Updated

Boulder Lake and Kentuck 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. The readings are close: Boulder Lake and Kentuck 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

Vilas County, Wisconsin

Murky, only visible to about 5.6 ft.

Kentuck Lake

Vilas County, Wisconsin

Moderate clarity, visible to about 9.5 ft.

Side-by-Side Metrics

MetricBoulder LakeKentuck Lake
Water Clarity5.6 ft9.5 ft Better
Phosphorus21.6 µg/L Better24.3 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth23 ft40 ft Better
Surface Area516 acres1,001 acres
Public AccessYesYes
Fish Species6 Better5
Trophic Stateeutrophicmesotrophic

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.

Verdict

Both lakes earn the same Grade B. The tiebreakers come down to clarity (Boulder Lake: 5.6 ft, Kentuck Lake: 9.5 ft) and what you want from the lake. Boulder Lake supports more documented fish species.

Source: EPA National Aquatic Resource Surveys, 2026.