Pat Lake
Pat Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 11 µg/L.
- Clarity
- 6.5 ft
- Typical in August
- 70°F
- Type
- Eutrophic
- Public access
- No
Next lake in Washington County
Pat Lake is a productive, nutrient-rich eutrophic lake in Washington County, Minnesota. Water quality is graded C based on 2 sampling years through 2024. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 74 other monitored lakes in Washington County, Pat Lake ranks #46 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-30. 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 6.5 ft. Phosphorus level: 39 µg/L. Chlorophyll-a: 11 µg/L. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.5 ft | Not graded |
| Phosphorus | 39 µg/L | Fair |
| Chlorophyll-a (Algae) | 11 µg/L | Fair |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Pat Lake
Compare lakeside cabins, hotels, and vacation rentals near Pat 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 Pat Lake
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Water Temperature
Pat Lake typically sits around 70°F at the surface in August. Summer average is about 70°F. Usually warmest in Jul (about 72°F) and coldest in Apr (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 264 field readings (2010–2024) via the EPA Water Quality Portal. See the full Pat Lake water temperature breakdown →
Fishing Pat Lake
EPA Impairment Status
Pat Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN82-0120-00 · Official waterbody report · Matched by proximity (0.93 km)
County Ranking
Ranked #46 of 75 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Pat Lake
What is the water quality grade for Pat Lake?
- Pat Lake in Washington County, Minnesota has a water quality grade of C (Fair). Water clarity: 6.5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 11 µg/L.
Is Pat Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Pat Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 11 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Pat Lake?
- Pat Lake typically sits around 70°F at the surface in August, from 264 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Explore Pat Lake across LakeGrade
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Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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Other Grade C Lakes in Minnesota
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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