Unnamed Lake
Unnamed Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2 ft visibility. Phosphorus: 518.5 µg/L. Chlorophyll-a (algae): 44.4 µg/L. Maximum depth: 15 ft. Surface area: 147.21 acres.
- Clarity
- 2 ft
- Max depth
- 15 ft
- Area
- 147 acres
- Public access
- Yes
Next lake in Big Stone County
Why Unnamed 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 Unnamed 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.
Unnamed Lake is a 147-acre lake in Big Stone County, Minnesota with a maximum depth of 15 feet. The lake supports 8 documented fish species including black bullhead, black crappie, and common carp. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-07-31. 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 Unnamed Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 2 ft of visibility. Phosphorus level: 518.5 µg/L. Chlorophyll-a: 44.4 µg/L. Trophic State Index: 76.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2 ft | Not graded |
| Phosphorus | 518.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 44.4 µg/L | Not graded |
| Trophic State Index (TSI) | 76 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Unnamed Lake
Compare lakeside cabins, hotels, and vacation rentals near Unnamed 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 Unnamed Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 15 ft |
| Surface Area | 147 acres |
| Shoreline Length | 4.6 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Recreation & Access
- Long Tom LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Unnamed Lake
DNR Fisheries Survey Summary
15 surveys on file from MN DNR Fisheries. Most recent: 2023-06-05 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Fathead Minnow | 476.27 | — |
| SUN | 135.38 | — |
| Common Carp | 125.97 | 1.53 lb |
| CRP | 115.33 | — |
| OTS | 112.67 | — |
| Black Bullhead | 93.12 | 0.19 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.
SUN
Common Carp
Black Bullhead
From the 2023-06-05 survey
Long Tom Lake is a 133-acre reservoir located three miles east and two miles north of Ortonville in Big Stone County. The lake is primarily managed for walleyes. A fishing pier and boat launch are located on the north side of the lake. A winterkill occurred during the winter of 2018-2019 even though an aeration system…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Unnamed Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Long TomFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Long TomFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Long TomPublic Water Access Sites · MN DNR LakeFinder
EPA Impairment Status
Unnamed 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 MN06-0060-00 · Official waterbody report
Graded lakes near Unnamed Lake
Unnamed Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Big Stone County
Frequently asked questions about Unnamed Lake
What is the water quality grade for Unnamed Lake?
- Unnamed Lake in Big Stone County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2 ft visibility. Phosphorus: 518.5 µg/L. Chlorophyll-a (algae): 44.4 µg/L. Maximum depth: 15 ft. Surface area: 147.21 acres.
Is Unnamed Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Unnamed Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 44.4 µg/L. Always check local health department advisories before swimming.
How deep is Unnamed Lake?
- Unnamed Lake has a maximum depth of 15 feet. The lake covers 147.21 acres.
What fish are in Unnamed Lake?
- Fish species found in Unnamed Lake include black bullhead, black crappie, common carp, orangespotted sunfish, suckers, walleye, white sucker, yellow perch. Unnamed Lake is located in Big Stone County, Minnesota.
Are there boat ramps on Unnamed Lake?
- Unnamed Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Long Tom Lake. Public access is listed as yes.
Explore Unnamed Lake across LakeGrade
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Where this data comes from
8 measurements from 2 monitoring stations, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA8 samples · 2022–2023
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 (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 details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory