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LakeQuality

Pillager Lake vs Thunder Lake

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

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

Both Pillager 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. These two are within a letter of each other on the rubric — Pillager Lake (A) versus Thunder Lake (A). 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.

A

Pillager Lake

Cass County, Minnesota

Crystal clear, you can see 15.1 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.

MetricPillager LakeThunder Lake
Overall GradeA (Excellent)A (Excellent)
Water Clarity15.1 ft16.4 ft
Phosphorus7 µg/L10 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area768 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 (Pillager Lake: 15.1 ft, Thunder Lake: 16.4 ft) and what you want from the lake. Pillager Lake matches its peer on species count.