Little Trout Lake
St. Louis County, Minnesota272 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Little Trout Lake. Here is what has been measured.
- Oligotrophic
- Impaired · Mercury
- 95 ft max depth
- Limited data
Little Trout Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 20.3 ft visibility. Phosphorus: 10.2 µg/L. Maximum depth: 95 ft. Surface area: 271.84 acres.
Minnesota DNR's Standard Survey on August 21, 2023 caught 2.50 walleye per gill net at Little Trout Lake. Length samples in the latest survey that recorded them ran 13–28 inches. DNR survey details →
Little Trout Lake is a 272-acre cold, clear oligotrophic lake in St. Louis County, Minnesota with a maximum depth of 95 feet (43-foot average). Overall water quality is declining over recent sampling years. The lake supports 8 documented fish species including cisco species, green sunfish, and lake trout. No public access — the lake is private or restricted. Compared to the 67 other monitored lakes in St. Louis County, Little Trout Lake ranks #34 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-08-26. Methodology: how these readings are compared.
What Little Trout Lake is good for
From access and monitoring records, not editorial picks.
- Clear water20.3 ft of visibility
- Fishing8 species recorded
- Deep water95 ft surveyed max depth
Swimming conditions
Readings onlyLimited data
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. Little Trout Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Little Trout 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 Little Trout Lake
These are the measurements Minnesota PCA publishes for Little Trout Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 20.3 ft down. Phosphorus 10.2 µg/L. TSI 36.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 20.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 10.2µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading 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. | 36 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Little Trout Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Little Trout Lake typically sits around 53°F at the surface in September. Summer average is about 53°F. Usually warmest in Jul (about 54°F) and coldest in Jun (about 51°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (51°F) to its warmest (54°F).
Typical surface water temperature by month, from 921 field readings (2010–2024) via the EPA Water Quality Portal. See the full Little Trout Lake water temperature breakdown →
Minnesota DNR's Standard Survey on August 21, 2023 caught 2.50 walleye per gill net at Little Trout Lake. Length samples in the latest survey that recorded them ran 13–28 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Little Trout Lake’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2023-08-21 (Standard Survey).
7 surveys on file · most recent 2023-08-21 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Rock Bass | 6.96 | 4–8 in 2023-08-21 | 0.19 lb |
| Walleye | 4.04 | 13–28 in 2023-08-21 | 3.49 lb |
| Smallmouth Bass | 2.99 | 5–18 in 2023-08-21 | 1.34 lb |
| Tullibee (Cisco) | 2.90 | 7–12 in 2009-08-10 | 0.19 lb |
| Yellow Perch | 2.50 | 6 in 2023-08-21 | 0.11 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.
Rock Bass
Walleye
Smallmouth Bass
Tullibee (Cisco)
From the 2023-08-21 survey
Little Trout Lake is a 272 acre lake located in Voyageurs National Park. Little Trout Lake has a maximum depth of 95 feet, and good water clarity. The Lake is accessed via a short but fairly steep portage between Grassy Bay of Sand Point Lake and the south end of Little Trout Lake. This diverse fishery supports…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Little Trout Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Little TroutFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Little TroutFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
95 ft
Average depth
42.8 ft
Surface area
272 acres
Shoreline
4.6 mi
Littoral zone
29%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,138 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
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Stays near Little Trout Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Little Trout Lake
- → Little Trout Lake fishing: DNR survey catch rates, species & stocking
- → Little Trout Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Little Trout Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Little Trout Lake? (mercury & PFAS guide)
Water Quality Trend: Worsening
Based on 5 years of monitoring (2020–2024).
Water clarity
Worsening5 years
Phosphorus
Worsening+5.65 µg/L/yr3 years
EPA Impairment Status
Little Trout Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN69-0682-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Little Trout Lake
Where is Little Trout Lake?
- Little Trout 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 Little Trout Lake?
- Little Trout Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 20.3 ft visibility. Phosphorus: 10.2 µg/L. Maximum depth: 95 ft. Surface area: 271.84 acres.
Is Little Trout Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Little Trout Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Little Trout Lake?
- Little Trout Lake typically sits around 53°F at the surface in September, from 921 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Little Trout Lake?
- Little Trout Lake has a maximum depth of 95 feet and an average depth of 42.8 feet. The lake covers 271.84 acres.
What fish are in Little Trout Lake?
- Fish species found in Little Trout Lake include cisco species, green sunfish, lake trout, northern pike, rock bass, smallmouth bass, walleye, yellow perch. Little Trout Lake is located in St. Louis County, Minnesota.
What did the DNR fisheries survey find at Little Trout Lake?
- Minnesota DNR's Standard Survey on August 21, 2023 caught 2.50 walleye per gill net at Little Trout Lake. Length samples in the latest survey that recorded them ran 13–28 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Little Trout Lake’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Little Trout Lake?
- Public access to Little Trout 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 Little Trout Lake across LakeQuality
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Where this data comes from
18 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- National Park Service Water Resources Division
11NPSWRD_WQX18 samples · 2020–2024
Analytical methods
- Secchi Disk
- Alkaline Persulfate Digestion for Total N and P in Water
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder