Otrey Lake
Otrey Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility. Phosphorus: 431 µg/L. Chlorophyll-a (algae): 156 µg/L. Maximum depth: 8 ft. Surface area: 475.26 acres.
- Clarity
- 1 ft
- Max depth
- 8 ft
- Area
- 475 acres
- Trend
- ↑ Improving
- Public access
- No
Next lake in Big Stone County
Why Otrey 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 Otrey Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, 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.
Otrey Lake is a 475-acre lake in Big Stone County, Minnesota with a maximum depth of 8 feet (5-foot average). Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including black bullhead, common carp, and orangespotted sunfish. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-06-27. 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 Otrey Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 1 ft of visibility. Phosphorus level: 431 µg/L. Chlorophyll-a: 156 µg/L. Trophic State Index: 83.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | Not graded |
| Phosphorus | 431 µg/L | Not graded |
| Chlorophyll-a (Algae) | 156 µg/L | Not graded |
| Trophic State Index (TSI) | 83 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Otrey Lake
Compare lakeside cabins, hotels, and vacation rentals near Otrey Lake in Big Stone 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 Otrey Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 8 ft |
| Average Depth | 5 ft |
| Surface Area | 475 acres |
| Shoreline Length | 8.1 mi |
| Littoral Zone | 100% |
| 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 Otrey Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2018-06-11 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Fathead Minnow | 324.20 | — |
| Black Bullhead | 52.18 | 0.09 lb |
| Common Carp | 19.42 | 0.7 lb |
| OSS | 1.85 | 0.03 lb |
| White Sucker | 1.68 | 0.49 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
Common Carp
OSS
White Sucker
From the 2018-06-11 survey
Otrey is a highly productive, 562-acre lake located six miles northeast of Ortonville in Big Stone County. No public boat access exists. Otrey's maximum depth was eight feet during 2018, which has been typical for years with average to above average precipitation. However, its maximum depth was only 3.5 feet in 1991…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Otrey Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OtreyFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.6 m/yr | 2 |
| Phosphorus | ↓ Declining | +369 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -139.2 µg/L/yr | 2 |
Graded lakes near Otrey Lake
Otrey Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Big Stone County
Frequently asked questions about Otrey Lake
What is the water quality grade for Otrey Lake?
- Otrey Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1 ft visibility. Phosphorus: 431 µg/L. Chlorophyll-a (algae): 156 µg/L. Maximum depth: 8 ft. Surface area: 475.26 acres.
Is Otrey Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Otrey Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 156 µg/L. Always check local health department advisories before swimming.
How deep is Otrey Lake?
- Otrey Lake has a maximum depth of 8 feet and an average depth of 5 feet. The lake covers 475.26 acres.
What fish are in Otrey Lake?
- Fish species found in Otrey Lake include black bullhead, common carp, orangespotted sunfish, white sucker. Otrey Lake is located in Big Stone County, Minnesota.
Explore Otrey Lake across LakeGrade
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Species activity outlook by water temperature and season
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Where this data comes from
4 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA4 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder