Thomas Lake
Dakota County, Minnesota41 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Thomas Lake. Here is what has been measured.
- Eutrophic
- Eurasian watermilfoil
- 8 ft max depth
- Public access
Thomas Lake in Dakota County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.6 ft visibility. Phosphorus: 26.5 µg/L. Chlorophyll-a (algae): 6.7 µg/L. Maximum depth: 8 ft. Surface area: 41.49 acres.
Minnesota DNR's Standard Survey on June 20, 2016 caught 0.40 largemouth bass per trap net at Thomas Lake. Length samples in the latest survey that recorded them ran 5–17 inches. DNR survey details →
Thomas Lake is a 41-acre productive, nutrient-rich eutrophic lake in Dakota County, Minnesota with a maximum depth of 8 feet. Overall water quality is declining over recent sampling years. The lake supports 6 documented fish species including black bullhead, black crappie, and bluegill. Public access is available. Compared to the 44 other monitored lakes in Dakota County, Thomas Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-23. Methodology: how these readings are compared.
What Thomas Lake is good for
From access and monitoring records, not editorial picks.
- Fishing6 species recorded
- Ice seasonIce-out around Apr 4
Swimming conditions
Readings onlyModerate algae
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 5.6 ft. Phosphorus 26.5 µg/L. Chlorophyll-a 6.7 µg/L. TSI 51.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 26.5µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 6.7µg/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. | 51 | 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 69°F at the surface in September. Summer average is about 77°F. Usually warmest in Jul (about 78°F) and coldest in Apr (about 52°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (52°F) to its warmest (78°F).
Typical surface water temperature by month, from 73 field readings (2010–2025) via the EPA Water Quality Portal. See the full Thomas Lake water temperature breakdown →
Minnesota DNR's Standard Survey on June 20, 2016 caught 0.40 largemouth bass per trap net at Thomas Lake. Length samples in the latest survey that recorded them ran 5–17 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Thomas Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2016-06-20 (Standard Survey).
2 surveys on file · most recent 2016-06-20 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Bluegill | 20.80 | 3–7 in 2016-06-20 | 0.12 lb |
| Largemouth Bass | 18.21 | 5–17 in 2016-06-20 | 1.09 lb |
| Golden Shiner | 2.40 | 6–8 in 2016-06-20 | 0.14 lb |
| Hybrid Sunfish | 2.00 | 6 in 2016-06-20 | 0.23 lb |
| Black Crappie | 1.80 | 4–9 in 2016-06-20 | 0.24 lb |
| Pumpkinseed | 0.60 | 6 in 2016-06-20 | 0.22 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Bluegill
Largemouth Bass
Golden Shiner
Hybrid Sunfish
From the 2016-06-20 survey
Thomas Lake (unnamed 19006700) is located in the City of Eagan at the Thomas Lake Park. The park is managed by The City of Eagan Parks and Thomas Lake is co-managed by the City of Eagan Lakes and Wetlands Program and the MN DNR. The park has a fishing pier, shore fishing stations, boat access, restrooms, ample…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Thomas Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — ThomasFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — ThomasFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ThomasPublic Water Access Sites · MN DNR LakeFinder
Lake Details
Max depth
8 ft
Surface area
41 acres
Shoreline
2.6 mi
Littoral zone
91%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
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Stays near Thomas Lake
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Top-rated places to stay near Thomas Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Thomas 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: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Worsening+1.27 µg/L/yr6 years
Chlorophyll-a
Worsening+0.42 µg/L/yr6 years
Ice season
Typical ice-out
Apr 4
Earliest Mar 25, 2007 · Latest Apr 16, 2008
Typical ice-in
Nov 27
Earliest Nov 14, 2005 · Latest Nov 30, 2021
Most recent ice-out
Apr 7
2022
14 observations · Minnesota PCA ice records
Nearby Lakes in Dakota County
Frequently asked questions about Thomas Lake
Where is Thomas Lake?
- Thomas Lake is a lake in Dakota 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 Dakota County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5.6 ft visibility. Phosphorus: 26.5 µg/L. Chlorophyll-a (algae): 6.7 µg/L. Maximum depth: 8 ft. Surface area: 41.49 acres.
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 69°F at the surface in September, from 73 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Thomas Lake?
- Thomas Lake has a maximum depth of 8 feet. The lake covers 41.49 acres.
What fish are in Thomas Lake?
- Fish species found in Thomas Lake include black bullhead, black crappie, bluegill, hybrid sunfish, largemouth bass, pumpkinseed. Thomas Lake is located in Dakota County, Minnesota.
What did the DNR fisheries survey find at Thomas Lake?
- Minnesota DNR's Standard Survey on June 20, 2016 caught 0.40 largemouth bass per trap net at Thomas Lake. Length samples in the latest survey that recorded them ran 5–17 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Thomas Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
When does Thomas Lake thaw?
- Thomas Lake typically has ice-out around Apr 4. Ice typically forms around Nov 27. The open water season is approximately 237 days.
Can I fish at Thomas Lake?
- Public access to Thomas Lake is listed as yes on the lake record. 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
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Where this data comes from
175 measurements from 3 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
MNPCA175 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity, Nephelometric Method
Monitoring station identifiers (3)
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
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate