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LakeQuality
C

Sunfish Lake

Washington County, MinnesotaLimited DataMesotrophic

Sunfish Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Among the 31 graded lakes in Washington County, Sunfish Lake sits at rank 14, above the county median.

Eurasian watermilfoil is established at Sunfish Lake, which can dampen recreational access and pressure the native plant community. The state fisheries records do not list documented species for Sunfish Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-27. Grade methodology: LakeGrade methodology.

Swimming Safety

Generally safe for swimming, moderate water quality

Water Quality Grade: C, Fair

Moderate clarity, visible to about 8.5 ft. Trophic State Index: 46.

MetricValueGrade
Water Clarity (Secchi Depth)8.5 ftC
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)46Mesotrophic

Moderate nutrients, good water quality

Invasive Species

Eurasian watermilfoil

Water Quality Trend: Declining

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.068 m/yr5

Location

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County Ranking

Ranked #14 of 31 lakes in Washington County

Nearby Lakes in Washington County

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2024-09-27

Monitoring stations: 1