Cotton Lake
Cotton Lake in Becker County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11.5 ft visibility. Maximum depth: 28 ft. Surface area: 1763.15 acres.
- Clarity
- 11.5 ft
- Typical in August
- 75°F
- Max depth
- 28 ft
- Area
- 1,763 acres
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 23
- Open water
- 216 days
Next lake in Becker County
Free interactive depth-contour map of Cotton Lake, reaching a maximum surveyed depth of 25 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Why Cotton Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Cotton Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Cotton Lake is a 1,763-acre lake in Becker County, Minnesota with a maximum depth of 28 feet. Overall water quality is improving over recent sampling years. The lake supports 15 documented fish species including black bullhead, black crappie, and bluegill. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-02. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Cotton Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 11.5 ft. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Cotton Lake
Compare lakeside cabins, hotels, and vacation rentals near Cotton 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.
Top-rated places to stay near Cotton Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Cotton Lake typically sits around 75°F at the surface in August. Summer average is about 72°F. Usually warmest in Aug (about 75°F) and coldest in Oct (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 70 field readings (2016–2025) via the EPA Water Quality Portal. See the full Cotton Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Cotton Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (159,956 cells/mL) on May 9, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 28 ft |
| Surface Area | 1,763 acres |
| Shoreline Length | 10.9 mi |
| Littoral Zone | 44% |
| 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 Cotton Lake
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2021-07-12 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 175.70 | — |
| MMS | 46.42 | — |
| Bluegill | 31.13 | 0.19 lb |
| Yellow Perch | 24.23 | 0.35 lb |
| BKF | 22.88 | — |
| Yellow Bass | 6.21 | 0.89 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
Yellow Perch
Yellow Bass
From the 2021-07-12 survey
Cotton Lake is a 1,763-acre lake located in Becker county 12 miles east of the city of Detroit Lakes. The lake possesses a heavily developed shoreline and receives high recreational use and fishing pressure from the surrounding area, particularly during the open water season. The Shelly Island Wildlife Management Area…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Cotton Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — CottonFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Cotton (1221)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — CottonFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — CottonPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.181 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (33 observations).
Estimated open water season: 216 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-24 (2012) | 2010-11-23 (2010) |
| Ice-In | 2011-11-20 (2011) | 2001-12-07 (2001) |
Most recent ice-out: 2025-04-17
EPA Impairment Status
Cotton 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 MN03-0286-00 · Official waterbody report
Graded lakes near Cotton Lake
Cotton Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Becker County
Frequently asked questions about Cotton Lake
What is the water quality grade for Cotton Lake?
- Cotton Lake in Becker County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11.5 ft visibility. Maximum depth: 28 ft. Surface area: 1763.15 acres.
Is Cotton Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Cotton Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Cotton Lake?
- Cotton Lake typically sits around 75°F at the surface in August, from 70 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Cotton Lake?
- Cotton Lake has a maximum depth of 28 feet. The lake covers 1763.15 acres.
What fish are in Cotton Lake?
- Fish species found in Cotton Lake include black bullhead, black crappie, bluegill, brown bullhead, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Cotton Lake is located in Becker County, Minnesota.
When does Cotton Lake thaw?
- Cotton Lake typically has ice-out around Apr 23. Ice typically forms around Nov 25. The open water season is approximately 216 days.
Does Cotton Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Cotton Lake (clouds, ice, or an off-season gap). The most recent reading was high (159,956 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Explore Cotton Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Becker County
Species activity outlook by water temperature and season
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Top lakes and where to stay in the Park Rapids Area area
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Red River of the North Watershed, ranked by water quality
Minnesota's cleanest and most-polluted lakes, ranked
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Where this data comes from
83 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
MNPCA83 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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