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LakeQuality

Big Carnelian Lake vs Unnamed Lake

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

Big Carnelian Lake has a higher water quality grade (B, Good) than Unnamed Lake (D, Poor). Both are in Washington County, Minnesota.

Both Big Carnelian Lake and Unnamed 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. Big Carnelian Lake (B) is materially cleaner than Unnamed Lake (D). 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 — Big Carnelian 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?

B

Big Carnelian Lake

Washington County, Minnesota

Good clarity, visible to about 14.5 ft.

D

Unnamed Lake

Washington County, Minnesota

Very murky, less than 1.6 ft of visibility.

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.

MetricBig Carnelian LakeUnnamed Lake
Overall GradeB (Good)D (Poor)
Water Clarity14.5 ft1.6 ft
PhosphorusNo data33 µg/L
Chlorophyll-a (Algae)No dataNo data
Maximum Depth66 ft60 ft
Surface Area457.03 acres1.8K acres
Public AccessYesYes
Fish Species11
Trophic Stateoligotrophiceutrophic

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

Verdict

Big Carnelian Lake wins on overall water quality with a Grade B versus Unnamed Lake's Grade D. Water clarity: 14.5 ft vs 1.6 ft. For fishing diversity, Big Carnelian Lake also leads with 1 species.