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LakeQuality

Clearwater Lake vs Long Island Lake

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

Clearwater Lake has a higher water quality grade (A, Excellent) than Long Island Lake (C, Fair). Both are in Cook County, Minnesota.

Both Clearwater Lake and Long Island 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. Clearwater Lake (A) is materially cleaner than Long Island Lake (C). A gap that wide is unlikely to close in a single year of remediation work; it reflects multi-decade differences in the lakes themselves.

For a recreational visitor, the wider grade gap is decisive — Clearwater Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?

A

Clearwater Lake

Cook County, Minnesota

Crystal clear, you can see 30 ft down.

C

Long Island Lake

Cook County, Minnesota

Moderate clarity, visible to about 8 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.

MetricClearwater LakeLong Island Lake
Overall GradeA (Excellent)C (Fair)
Water Clarity30 ft8 ft
Phosphorus4 µg/LNo data
Chlorophyll-a (Algae)No dataNo data
Maximum Depth65 ft85 ft
Surface Area461.73 acres883.53 acres
Public AccessNoNo
Fish Species01
Trophic Stateoligotrophicmesotrophic

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

Verdict

Clearwater Lake wins on overall water quality with a Grade A versus Long Island Lake's Grade C. Water clarity: 30 ft vs 8 ft. For more fish-species variety, Long Island Lake edges ahead with 1 documented species.