Big Cormorant Lake
Big Cormorant Lake in Becker County, Minnesota has a water quality grade of A (Excellent). Water clarity: 24.8 ft visibility. Phosphorus: 16.5 µg/L. Chlorophyll-a (algae): 2.2 µg/L. Maximum depth: 75 ft. Surface area: 3657.12 acres.
- Clarity
- 24.8 ft
- Max depth
- 75 ft
- Area
- 3,657 acres
- Type
- Oligotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 19
- Open water
- 224 days
Next lake in Becker County
Free interactive depth-contour map of Big Cormorant Lake, reaching a maximum surveyed depth of 70 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Big Cormorant Lake is a 3,657-acre cold, clear oligotrophic lake in Becker County, Minnesota with a maximum depth of 75 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 16 documented fish species including black bullhead, black crappie, and bluegill. Public access is available. Compared to the 83 other monitored lakes in Becker County, Big Cormorant Lake ranks #25 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. 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 24.8 ft down. Phosphorus level: 16.5 µg/L. Chlorophyll-a: 2.2 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 24.8 ft | Not graded |
| Phosphorus | 16.5 µg/L | Good |
| Chlorophyll-a (Algae) | 2.2 µg/L | Good |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Big Cormorant Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Cormorant Lake in Becker 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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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 75 ft |
| Surface Area | 3,657 acres |
| Shoreline Length | 18.7 mi |
| Littoral Zone | 22% |
| Public Access | Yes |
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 Big Cormorant 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
21 surveys on file from MN DNR Fisheries. Most recent: 2025-08-25 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| MMS | 63.70 | — |
| Bluntnose Minnow | 22.48 | — |
| Rock Bass | 15.99 | 0.44 lb |
| Largemouth Bass | 14.43 | 0.95 lb |
| Walleye | 12.67 | 1.64 lb |
| Bluegill | 9.43 | 0.3 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.
Rock Bass
Largemouth Bass
Walleye
Bluegill
From the 2025-08-25 survey
Big Cormorant is a 3,657-acre lake located in southwestern Becker County. It is well-suited to Walleyes, which were reportedly introduced during the early part of the 20th century. A targeted fisheries survey using 12 gill nets was completed in August 2025 to assess the Walleye population of Big Cormorant Lake. Gill…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Cormorant 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 CormorantFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Big Cormorant (1198)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — Big CormorantFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Big CormorantPublic 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 | +0.189 m/yr | 6 |
| Phosphorus | ↓ Declining | +1.01 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +0.17 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (76 observations).
Estimated open water season: 224 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2010-04-02 (2010) | 2013-05-15 (2013) |
| Ice-In | 1990-11-11 (1990) | 2001-12-19 (2001) |
Most recent ice-out: 2023-05-10
EPA Impairment Status
Big Cormorant 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 MN03-0576-00 · Official waterbody report
County Ranking
Ranked #25 of 84 lakes in Becker County
Nearby Lakes in Becker County
Frequently asked questions about Big Cormorant Lake
What is the water quality grade for Big Cormorant Lake?
- Big Cormorant Lake in Becker County, Minnesota has a water quality grade of A (Excellent). Water clarity: 24.8 ft visibility. Phosphorus: 16.5 µg/L. Chlorophyll-a (algae): 2.2 µg/L. Maximum depth: 75 ft. Surface area: 3657.12 acres.
Is Big Cormorant Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Big Cormorant Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.2 µg/L. Always check local health department advisories before swimming.
How deep is Big Cormorant Lake?
- Big Cormorant Lake has a maximum depth of 75 feet. The lake covers 3657.12 acres.
What fish are in Big Cormorant Lake?
- Fish species found in Big Cormorant Lake include black bullhead, black crappie, bluegill, brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Big Cormorant Lake is located in Becker County, Minnesota.
When does Big Cormorant Lake thaw?
- Big Cormorant Lake typically has ice-out around Apr 19. Ice typically forms around Nov 29. The open water season is approximately 224 days.
Explore Big Cormorant Lake across LakeGrade
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Where this data comes from
168 measurements from 2 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
MNPCA168 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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