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LakeQuality

Pine Mountain Lake vs Thunder Lake

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

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

Pine Mountain Lake and Thunder Lake are both in Minnesota — 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 grades are close: Pine Mountain 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

Pine Mountain Lake

Cass County, Minnesota

Crystal clear, you can see 17.5 ft down.

A

Thunder Lake

Cass County, Minnesota

Crystal clear, you can see 16.4 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.

MetricPine Mountain LakeThunder Lake
Overall GradeA (Excellent)A (Excellent)
Water Clarity17.5 ft16.4 ft
PhosphorusNo data10 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area1.6K 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 (Pine Mountain Lake: 17.5 ft, Thunder Lake: 16.4 ft) and what you want from the lake. Pine Mountain Lake matches its peer on species count.