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LakeQuality

Thunder Lake vs Thunder Lake

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

Thunder Lake and Thunder Lake both received the same overall water quality grade of A (Excellent). Both are in Cass County, Minnesota.

Both Thunder Lake and Thunder Lake sit in Minnesota. 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: Thunder Lake (A) and Thunder Lake (A) 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.

A

Thunder Lake

Cass County, Minnesota

Crystal clear, you can see 16.4 ft down.

A

Thunder Lake

Cass County, Minnesota

Crystal clear, you can see 20 ft down.

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.

MetricThunder LakeThunder Lake
Overall GradeA (Excellent)A (Excellent)
Water Clarity16.4 ft20 ft
Phosphorus10 µg/LNo data
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area1.3K acres1.3K acres
Public AccessUnknownUnknown
Fish Species11
Trophic Stateoligotrophicoligotrophic

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

Verdict

Both lakes earn the same Grade A. The tiebreakers come down to clarity (Thunder Lake: 16.4 ft, Thunder Lake: 20 ft) and what you want from the lake. Thunder Lake matches its peer on species count.