Little Trout Lake
Little Trout Lake in St. Louis County, Minnesota has a water quality grade of B (Good). Water clarity: 20.3 ft visibility. Phosphorus: 10.2 µg/L. Maximum depth: 95 ft. Surface area: 271.84 acres.
- Clarity
- 20.3 ft
- Typical in August
- 53°F
- Max depth
- 95 ft
- Area
- 272 acres
- Type
- Oligotrophic
- Trend
- ↓ Declining
- Public access
- No
Next lake in St. Louis County
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). Water quality is graded B based on 1 sampling years through 2024. 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. Grade methodology: LakeGrade methodology.
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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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Crystal clear, you can see 20.3 ft down. Phosphorus level: 10.2 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 20.3 ft | Not graded |
| Phosphorus | 10.2 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Little Trout Lake
Compare lakeside cabins, hotels, and vacation rentals near Little Trout Lake in St. Louis 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.
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Water Temperature
Little Trout Lake typically sits around 53°F at the surface in August. 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.
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 →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 95 ft |
| Average Depth | 42.8 ft |
| Surface Area | 272 acres |
| Shoreline Length | 4.6 mi |
| Littoral Zone | 29% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Little Trout Lake
DNR Fisheries Survey Summary
7 surveys on file from MN DNR Fisheries. Most recent: 2023-08-21 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CIS | 10.25 | 0.67 lb |
| Rock Bass | 6.96 | 0.19 lb |
| Walleye | 4.04 | 3.49 lb |
| Smallmouth Bass | 2.99 | 1.34 lb |
| Tullibee (Cisco) | 2.90 | 0.19 lb |
| Yellow Perch | 2.50 | 0.11 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
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.
CIS
Rock Bass
Walleye
Smallmouth Bass
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
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.187 m/yr | 5 |
| Phosphorus | ↓ Declining | +5.65 µg/L/yr | 3 |
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN69-0682-00 · Official waterbody report
County Ranking
Ranked #34 of 68 lakes in St. Louis County
Nearby Lakes in St. Louis County
Frequently asked questions about Little Trout Lake
What is the water quality grade for Little Trout Lake?
- Little Trout Lake in St. Louis County, Minnesota has a water quality grade of B (Good). 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?
- Good for swimming, clear water with low algae levels. Little Trout Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Little Trout Lake?
- Little Trout Lake typically sits around 53°F at the surface in August, 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.
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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)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder