Sunfish Lake
Washington County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Sunfish Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- Eurasian watermilfoil
- 39 ft max depth
- Limited data
Sunfish Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.9 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7.2 µg/L.
Sunfish Lake is a mesotrophic lake in Washington County, Minnesota with an estimated average depth of about 39 feet. 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. Methodology: how these readings are compared.
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Sunfish Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Sunfish Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Sunfish Lake
These are the measurements Minnesota PCA publishes for Sunfish Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 8.9 ft. Phosphorus 25 µg/L. Chlorophyll-a 7.2 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 8.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 25µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 7.2µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 49 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Sunfish Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Sunfish Lake typically sits around 57°F at the surface in October. 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.
Column height runs from this lake’s coldest month (56°F) to its warmest (80°F).
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
Max depth
~39 ft est.
Public access
No
Listed by Minnesota PCA
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Sunfish Lake.
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Surface area
59 acres
HydroLAKES / HydroSHEDS
Shoreline
1.5 mi
HydroLAKES / HydroSHEDS
Elevation
889 ft
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.
Stays via Stay22
Stays 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
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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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 (2020–2025).
Water clarity
Stable6 years
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
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN82-0107-00 · Official waterbody report
Nearby Lakes in Washington County
Frequently asked questions about Sunfish Lake
Where is Sunfish Lake?
- Sunfish Lake is a lake in Washington County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Sunfish Lake?
- Sunfish Lake in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 8.9 ft visibility. Phosphorus: 25 µg/L. Chlorophyll-a (algae): 7.2 µg/L.
Is Sunfish Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Sunfish Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Sunfish Lake?
- Sunfish Lake typically sits around 57°F at the surface in October, 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 39 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Can I fish at Sunfish Lake?
- Public access to Sunfish Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Sunfish Lake across LakeQuality
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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