Big Trout Lake
Big Trout Lake in Crow Wing County, Minnesota has a water quality grade of A (Excellent). Water clarity: 16.9 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Maximum depth: 128 ft. Surface area: 1366.29 acres.
- Clarity
- 16.9 ft
- Typical in August
- 76°F
- Max depth
- 128 ft
- Area
- 1,366 acres
- Type
- Oligotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 29
Next lake in Crow Wing County
Free interactive depth-contour map of Big Trout Lake, reaching a maximum surveyed depth of 120 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Big Trout Lake is a 1,366-acre cold, clear oligotrophic lake in Crow Wing County, Minnesota with a maximum depth of 128 feet (52-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 20 documented fish species including black crappie, bluegill, and bowfin (dogfish). Public access is available. Compared to the 84 other monitored lakes in Crow Wing County, Big Trout Lake ranks #30 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-14. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Crystal clear, you can see 16.9 ft down. Phosphorus level: 10 µg/L. Chlorophyll-a: 2.1 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.9 ft | Not graded |
| Phosphorus | 10 µg/L | Good |
| Chlorophyll-a (Algae) | 2.1 µg/L | Good |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Big Trout Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Trout Lake in Crow Wing 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
Big Trout Lake typically sits around 76°F at the surface in August. Summer average is about 75°F. Usually warmest in Jul (about 77°F) and coldest in May (about 58°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 14 field readings (2021–2025) via the EPA Water Quality Portal. See the full Big Trout Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 128 ft |
| Average Depth | 52 ft |
| Surface Area | 1,366 acres |
| Shoreline Length | 8.9 mi |
| Littoral Zone | 27% |
| Public Access | Yes |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big Trout 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.
DNR Fisheries Survey Summary
19 surveys on file from MN DNR Fisheries. Most recent: 2024-07-22 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CNM | 64.33 | — |
| Bluntnose Minnow | 32.30 | — |
| BKF | 24.42 | — |
| JND | 23.86 | — |
| Bluegill | 15.67 | 0.09 lb |
| Tullibee (Cisco) | 13.02 | 0.14 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.
Bluegill
Tullibee (Cisco)
From the 2024-07-22 survey
Big trout is a 1,366 acre lake and is a part of the 14,000-acre Whitefish Chain of lakes in northern Crow Wing County. The maximum depth is 128 feet and 27% of the lake is 15 feet deep or less. On the east shore of the lake there is a U.S. Army Corps of Engineer's access off County Road 66. Big Trout is unique as it…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Trout Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Big TroutFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Big Trout (0436)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Big TroutFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Big TroutPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.111 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.59 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.05 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (7 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2021-04-07 (2021) | 2013-05-14 (2013) |
| Ice-In | 2022-12-09 (2022) | 2022-12-09 (2022) |
Most recent ice-out: 2025-04-22
EPA Impairment Status
Big 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 MN18-0315-00 · Official waterbody report
County Ranking
Ranked #30 of 85 lakes in Crow Wing County
Nearby Lakes in Crow Wing County
Frequently asked questions about Big Trout Lake
What is the water quality grade for Big Trout Lake?
- Big Trout Lake in Crow Wing County, Minnesota has a water quality grade of A (Excellent). Water clarity: 16.9 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 2.1 µg/L. Maximum depth: 128 ft. Surface area: 1366.29 acres.
Is Big Trout Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Big Trout Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.1 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Big Trout Lake?
- Big Trout Lake typically sits around 76°F at the surface in August, from 14 EPA Water Quality Portal field readings (2021–2025). That is a typical value for the month, not a live reading.
How deep is Big Trout Lake?
- Big Trout Lake has a maximum depth of 128 feet and an average depth of 52 feet. The lake covers 1366.29 acres.
What fish are in Big Trout Lake?
- Fish species found in Big Trout Lake include black crappie, bluegill, bowfin (dogfish), brown bullhead, greater redhorse, green sunfish, hybrid sunfish, lake trout, lake whitefish, largemouth bass, northern pike, pumpkinseed, rock bass, shorthead redhorse, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Big Trout Lake is located in Crow Wing County, Minnesota.
When does Big Trout Lake thaw?
- Big Trout Lake typically has ice-out around Apr 29.
Explore Big Trout Lake across LakeGrade
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Where this data comes from
112 measurements from 4 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
MNPCA112 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (4)
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
Ice data from Minnesota DNR Climate