Twin Lake
Twin Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 13 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
- Clarity
- 13 ft
- Typical in August
- 65°F
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- No
Next lake in Washington County
Twin Lake is a mesotrophic lake in Washington County, Minnesota. Water quality is graded A 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, Twin Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-14. Grade methodology: LakeGrade methodology.
Watch Twin Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 13 ft. Phosphorus level: 13 µg/L. Chlorophyll-a: 2.8 µg/L. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13 ft | Not graded |
| Phosphorus | 13 µg/L | Good |
| Chlorophyll-a (Algae) | 2.8 µg/L | Good |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Twin Lake
Compare lakeside cabins, hotels, and vacation rentals near Twin 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 Twin Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Twin Lake typically sits around 65°F at the surface in August. Summer average is about 62°F. Usually warmest in Aug (about 65°F) and coldest in Apr (about 44°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 Twin Lake water temperature breakdown →
Fishing Twin Lake
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.083 m/yr | 6 |
EPA Impairment Status
Twin 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 MN82-0049-00 · Official waterbody report · Matched by proximity (1.78 km)
County Ranking
Ranked #1 of 75 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Twin Lake
What is the water quality grade for Twin Lake?
- Twin Lake in Washington County, Minnesota has a water quality grade of A (Excellent). Water clarity: 13 ft visibility. Phosphorus: 13 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
Is Twin Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Twin Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Twin Lake?
- Twin Lake typically sits around 65°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 Twin Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the St. Croix Watershed, ranked by water quality
Moderate nutrients, good water quality
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Twin Lake
Other Grade A Lakes in Minnesota
Mesotrophic Lakes in Minnesota
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