Thomas Lake
Hennepin County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Thomas Lake. Here is what has been measured.
- Eutrophic
Thomas Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.4 ft visibility. Phosphorus: 78.3 µg/L. Chlorophyll-a (algae): 34.1 µg/L.
Thomas Lake is a productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Thomas Lake ranks #68 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-09-20. Methodology: how these readings are compared.
Swimming conditions
Readings onlyAlgae risk
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. Check local advisories before you swim.
Whether Thomas 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 Thomas Lake
These are the measurements Minnesota PCA publishes for Thomas Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.4 ft. Phosphorus 78.3 µg/L. Chlorophyll-a 34.1 µg/L. TSI 64.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 78.3µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 34.1µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 64 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Thomas Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Thomas Lake typically sits around 58°F at the surface in October. Summer average is about 57°F. Usually warmest in Aug (about 59°F) and coldest in Apr (about 40°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (40°F) to its warmest (59°F).
Typical surface water temperature by month, from 109 field readings (2021–2022) via the EPA Water Quality Portal. See the full Thomas Lake water temperature breakdown →
Stays via Stay22
Stays near Thomas Lake
Compare lakeside cabins, hotels, and vacation rentals near Thomas Lake in Hennepin 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Thomas Lake are listed below.
Top-rated places to stay near Thomas Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 →
Follow Thomas Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Thomas Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2020–2024).
Water clarity
Improving5 years
Phosphorus
Improving-36.64 µg/L/yr5 years
Chlorophyll-a
Improving-20.31 µg/L/yr5 years
Nearby Lakes in Hennepin County
Frequently asked questions about Thomas Lake
Where is Thomas Lake?
- Thomas Lake is a lake in Hennepin County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Thomas Lake?
- Thomas Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 3.4 ft visibility. Phosphorus: 78.3 µg/L. Chlorophyll-a (algae): 34.1 µg/L.
Is Thomas Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Thomas Lake?
- Thomas Lake typically sits around 58°F at the surface in October, from 109 EPA Water Quality Portal field readings (2021–2022). That is a typical value for the month, not a live reading.
Can I fish at Thomas Lake?
- Public access to Thomas 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 Thomas Lake across LakeQuality
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Hennepin County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the Crow River Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
More lakes in Minnesota
State Parks Near Thomas Lake
Other Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
52 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA52 samples · 2021–2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 4500 N C ~ Persufate Method for Total Nitrogen
Monitoring station identifiers (1)
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.