Sunfish Lake
Sunfish Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 8.9 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7.2 µg/L.
- Clarity
- 8.9 ft
- Typical in August
- 78°F
- Mean depth
- ~13 ft est.
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- No
Next lake in Washington County
Sunfish Lake is a mesotrophic lake in Washington County, Minnesota with an estimated average depth of about 13 feet. Water quality is graded C based on 2 sampling years through 2025. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 74 other monitored lakes in Washington County, Sunfish Lake ranks #33 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-07. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 8.9 ft. Phosphorus level: 25 µg/L. Chlorophyll-a: 7.2 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.9 ft | Not graded |
| Phosphorus | 25 µg/L | Fair |
| Chlorophyll-a (Algae) | 7.2 µg/L | Good |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Sunfish Lake
Compare lakeside cabins, hotels, and vacation rentals near Sunfish Lake in Washington County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Sunfish Lake
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Water Temperature
Sunfish Lake typically sits around 78°F at the surface in August. Summer average is about 76°F. Usually warmest in Jul (about 80°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 46 field readings (2011–2025) via the EPA Water Quality Portal. See the full Sunfish Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~13 ft est. |
| Public Access | No |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Sunfish Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Sunfish Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.011 m/yr | 6 |
EPA Impairment Status
Sunfish Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN82-0107-00 · Official waterbody report
County Ranking
Ranked #33 of 75 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Sunfish Lake
What is the water quality grade for Sunfish Lake?
- Sunfish Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 8.9 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7.2 µg/L.
Is Sunfish Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Sunfish Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 7.2 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Sunfish Lake?
- Sunfish Lake typically sits around 78°F at the surface in August, from 46 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Sunfish Lake?
- No published bathymetric survey covers Sunfish Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 13 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Sunfish Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
50 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA50 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
Monitoring station identifiers (2)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder