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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 (A, Excellent) 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. The grades are meaningfully apart: Big Carnelian Lake grades a A while Unnamed Lake grades a D. That two-letter spread reflects real underlying differences — different watershed inputs, different depth profiles, or different monitoring rigor.

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?

A

Big Carnelian Lake

Washington County, Minnesota

Crystal clear, you can see 15 ft down.

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 GradeA (Excellent)D (Poor)
Water Clarity15 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 A versus Unnamed Lake's Grade D. Water clarity: 15 ft vs 1.6 ft. For fishing diversity, Big Carnelian Lake also leads with 1 species.