Fish Lake
Fish Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 5 ft visibility. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
- Clarity
- 5 ft
- Typical in August
- 76°F
- Max depth
- ~28 ft est.
- Type
- Mesotrophic
- Public access
- Yes
Next lake in Washington County
Fish Lake is a mesotrophic lake in Washington County, Minnesota with an estimated average depth of about 28 feet. Water quality is graded C based on 2 sampling years through 2024. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 74 other monitored lakes in Washington County, Fish Lake ranks #27 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-14. 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)
Murky, only visible to about 5 ft. Phosphorus level: 26 µg/L. Chlorophyll-a: 3.6 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | 26 µg/L | Fair |
| Chlorophyll-a (Algae) | 3.6 µg/L | Good |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Fish Lake
Compare lakeside cabins, hotels, and vacation rentals near Fish 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 Fish Lake
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Water Temperature
Fish Lake typically sits around 76°F at the surface in August. Summer average is about 75°F. Usually warmest in Jul (about 78°F) and coldest in Apr (about 47°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 50 field readings (2010–2024) via the EPA Water Quality Portal.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~28 ft est. |
| Average Depth | ~13 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Fish 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.
Recreation & Access
- Big Marine Lake (North)Public
Fishing Fish Lake
EPA Impairment Status
Fish 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 MN82-0064-00 · Official waterbody report
County Ranking
Ranked #27 of 75 lakes in Washington County
Nearby Lakes With Higher Grades
Fish Lake holds Grade C. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Washington County
Frequently asked questions about Fish Lake
What is the water quality grade for Fish Lake?
- Fish Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 5 ft visibility. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 3.6 µg/L.
Is Fish Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Fish Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 3.6 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Fish Lake?
- Fish Lake typically sits around 76°F at the surface in August, from 50 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Fish Lake?
- No published bathymetric survey covers Fish Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 28 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Fish Lake?
- Fish Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Marine Lake (North). Public access is listed as yes.
Explore Fish Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
28 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA28 samples · 2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
Monitoring station identifiers (1)
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
Named boat-access points from the USGS National Boat Ramps inventory