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LakeQuality

Blacktail Dam Lake vs Kota Ray Dam Lake

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

Kota Ray Dam Lake has a higher water quality grade (B, Good) than Blacktail Dam Lake (B, Good). Both are in Williams County, Wisconsin.

Both Blacktail Dam Lake and Kota Ray Dam Lake sit in North Dakota. 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 close: Blacktail Dam Lake (B) and Kota Ray Dam Lake (B) are within one letter of each other on the LakeGrade rubric. The per-parameter sub-grades below will show where the small differences actually live.

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.

B

Blacktail Dam Lake

Williams County, Wisconsin

Moderate clarity, visible to about 7.2 ft.

B

Kota Ray Dam Lake

Williams County, Wisconsin

Moderate clarity, visible to about 7.7 ft.

Side-by-Side Metrics

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

Source: EPA National Aquatic Resource Surveys, 2026.

MetricBlacktail Dam LakeKota Ray Dam Lake
Overall GradeB (Good)B (Good)
Water Clarity7.2 ft7.7 ft
PhosphorusNo dataNo data
Chlorophyll-a (Algae)8.6 µg/L3.5 µg/L
Maximum Depth--
Surface Area158 acres27.7 acres
Public AccessUnknownUnknown
Fish Species00
Trophic Stateeutrophicmesotrophic

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

Verdict

Kota Ray Dam Lake wins on overall water quality with a Grade B versus Blacktail Dam Lake's Grade B. Water clarity: 7.7 ft vs 7.2 ft. For fishing diversity, Kota Ray Dam Lake also leads with 0 species.