Trease Lake
St. Louis County, Minnesota97 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Trease Lake. Here is what has been measured.
- Limited data
Trease Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.7 ft visibility. Phosphorus: 29 µg/L. Chlorophyll-a (algae): 8.2 µg/L. Surface area: 96.85 acres.
Minnesota DNR's Standard Survey on September 2, 2014 caught 3.17 northern pike per gill net at Trease Lake. Length samples in the latest survey that recorded them ran 11–26 inches. DNR survey details →
Trease Lake is a 97-acre lake in St. Louis County, Minnesota. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including largemouth bass, northern pike, and smallmouth bass. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-07-28. Methodology: how these readings are compared.
What Trease Lake is good for
From access and monitoring records, not editorial picks.
- Fishing4 species recorded
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Trease 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 Trease Lake
These are the measurements Minnesota PCA publishes for Trease 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 4.7 ft. Phosphorus 29 µg/L. Chlorophyll-a 8.2 µg/L. TSI 53.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 29µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 8.2µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 53 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Trease Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on September 2, 2014 caught 3.17 northern pike per gill net at Trease Lake. Length samples in the latest survey that recorded them ran 11–26 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Trease Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 2014-09-02 (Standard Survey).
1 survey on file · most recent 2014-09-02 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Northern Pike | 3.17 | 11–26 in 2014-09-02 | 2.01 lb |
| Smallmouth Bass | 1.33 | 6–15 in 2014-09-02 | 0.53 lb |
| Largemouth Bass | 1.00 | 10–15 in 2014-09-02 | 1.03 lb |
| White Sucker | 0.33 | 18–20 in 2014-09-02 | 3.03 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.
Northern Pike
Smallmouth Bass
Largemouth Bass
White Sucker
From the 2014-09-02 survey
Erickson Lake is located approximately 10 miles N of Ely and is entirely within the BWCAW. Lake levels at the time of the assessment were approximately 1.5 feet below average and the shoreline was defined by woody debris with exposed boulders and muck. Access is by a 180 rod portage from North Hegman Lake. There are 3…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Trease Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — EricksonFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Surface area
97 acres
Shoreline
4.8 mi
Public access
No
Listed by Minnesota PCA
No bathymetric survey has been published for Trease Lake, so its depth is not documented here.
Stays via Stay22
Stays near Trease Lake
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Follow Trease Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Trease Lake
Water quality readings over time
2 seasons of samples on record (2022–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Nearby Lakes in St. Louis County
Frequently asked questions about Trease Lake
Where is Trease Lake?
- Trease Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Trease Lake?
- Trease Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.7 ft visibility. Phosphorus: 29 µg/L. Chlorophyll-a (algae): 8.2 µg/L. Surface area: 96.85 acres.
Is Trease Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What fish are in Trease Lake?
- Fish species found in Trease Lake include largemouth bass, northern pike, smallmouth bass, white sucker. Trease Lake is located in St. Louis County, Minnesota.
What did the DNR fisheries survey find at Trease Lake?
- Minnesota DNR's Standard Survey on September 2, 2014 caught 3.17 northern pike per gill net at Trease Lake. Length samples in the latest survey that recorded them ran 11–26 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Trease Lake’s water-quality measurements separately, and the water-quality trend over 2 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Trease Lake?
- Public access to Trease 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.
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Where this data comes from
5 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA5 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- 2120 B ~ Color in Water by Visual Comparison
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.
Other records on this page
Lake details from Minnesota DNR LakeFinder