Sleepy Eye Lake
Brown County, MinnesotaEutrophic
Sleepy Eye Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota average. Secchi readings are the weakest of the scored parameters, suggesting suspended sediment or algal biomass dominates the optical signal.
A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. The lake bottoms out at 21 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake's 241 acres and 4.3 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Among the 7 graded lakes in Brown County, Sleepy Eye Lake sits at rank 2, above the county median.
No invasive species are currently listed at Sleepy Eye Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye among the lake's 10 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 15 observed ice-outs, centered near Mar 27. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-10-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 3.3 ft of visibility. Phosphorus level: 39.5 µg/L. Chlorophyll-a: 41.7 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.3 ft | F |
| Phosphorus | 39.5 µg/L | C |
| Chlorophyll-a (Algae) | 41.7 µg/L | F |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 21 ft |
| Average Depth | 7 ft |
| Surface Area | 240.82 acres |
| Shoreline Length | 4.3 mi |
| Littoral Zone | 84% |
| Public Access | Yes |
Fish Species
Click a species to see all Minnesota and Wisconsin lakes where it is found.
→ Best fishing times for Sleepy Eye Lake (14-day solunar calendar)
→ Is it safe to eat fish from Sleepy Eye Lake? (mercury & PFAS guide)
→ Sleepy Eye Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.151 m/yr | 4 |
| Phosphorus | ↓ Declining | +13.95 µg/L/yr | 4 |
Ice Season
Historical ice data from Minnesota DNR (28 observations).
Estimated open water season: 243 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-03-06 (2017) | 2013-04-18 (2013) |
| Ice-In | 1991-11-05 (1991) | 2015-12-18 (2015) |
Most recent ice-out: 2019-04-08
Location
County Ranking
Ranked #2 of 7 lakes in Brown County
Cleaner Lakes Within 30 Miles
Sleepy Eye Lake holds Grade D. 2 nearby lakes hold higher grades.
- DWellner-Hageman ReservoirBrown County · mi · Higher overall water quality score
- DFedji LakeWatonwan County · mi · Higher overall water quality score
Nearby Lakes in Brown County
More Minnesota Lake Rankings
State Parks Near Sleepy Eye Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
DNR Fisheries Survey Summary
18 surveys on file from MN DNR Fisheries. Most recent: 2021-08-16 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 116.05 | 0.47 lb |
| Bluegill | 31.13 | 0.16 lb |
| White Crappie | 26.64 | 0.32 lb |
| Yellow Perch | 20.59 | 0.15 lb |
| Black Crappie | 14.73 | 0.24 lb |
| Largemouth Bass | 8.97 | 1.53 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.
Black Bullhead
Bluegill
Yellow Perch
Black Crappie
From the 2021-08-16 survey
Sleepy Eye is a smaller sized lake (240 acres) located adjacent to the City of Sleepy Eye in Brown County. A large city-owned access with a double cement boat ramp is located on the north shore within the Sleepy Eye Sportsmen's Park. Sleepy Eye Lake has 4 miles of shoreline and a maximum depth of 21 feet. The…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Sleepy Eye Lake. 3 reports on file.
- —Fisheries Lake Survey — Sleepy EyeFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Sleepy EyeFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Sleepy EyePublic Water Access Sites · MN DNR LakeFinder
Reservoir Info (USACE NID)
Sleepy Eye Lake is a man-made reservoir impounded by the Sleepy Eye Control (completed 1949), built primarily for recreation on the County Ditch 5; gravity-type dam, 8 ft tall and 35 ft long.
- Surface area
- 227 ac
- Normal storage
- 2,300 ac-ft
- Max storage
- 2,975 ac-ft
- Drainage area
- 1.5 sq mi
- Hazard class
- Low
- Owner
- City of Sleepy Eye
Source: USACE National Inventory of Dams, NID ID MN00754 · Operator website · Matched by proximity (0.36 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate
Most recent sample: 2023-10-11
Monitoring stations: 1