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LakeQuality

Echo Lake vs Thomson Reservoir

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

Echo Lake has a higher water quality grade (B, Good) than Thomson Reservoir (F, Very Poor). Both are in Carlton County, Minnesota.

Echo Lake and Thomson Reservoir 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. Echo Lake (B) is materially cleaner than Thomson Reservoir (F). 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 — Echo 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

Echo Lake

Carlton County, Minnesota

Good clarity, visible to about 11 ft.

F

Thomson Reservoir

Carlton County, Minnesota

Very murky, less than 3 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.

MetricEcho LakeThomson Reservoir
Overall GradeB (Good)F (Very Poor)
Water Clarity11 ft3 ft
PhosphorusNo dataNo data
Chlorophyll-a (Algae)No dataNo data
Maximum Depth--
Surface Area10 acres375 acres
Public AccessUnknownUnknown
Fish Species11
Trophic Statemesotrophiceutrophic

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

Verdict

Echo Lake wins on overall water quality with a Grade B versus Thomson Reservoir's Grade F. Water clarity: 11 ft vs 3 ft. For fishing diversity, Echo Lake also leads with 1 species.