Oslo Lake
Oslo Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9.2 ft visibility. Maximum depth: 36 ft. Surface area: 99.24 acres.
- Clarity
- 9.2 ft
- Max depth
- 36 ft
- Area
- 99 acres
- Trend
- ↓ Declining
- Public access
- No
Next lake in St. Louis County
Why Oslo 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 Oslo Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). 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.
Oslo Lake is a 99-acre lake in St. Louis County, Minnesota with a maximum depth of 36 feet. Overall water quality is declining over recent sampling years. The lake supports 2 documented fish species including northern pike and yellow perch. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2023-08-08. 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 Oslo Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Moderate clarity, visible to about 9.2 ft. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.2 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Oslo Lake
Compare lakeside cabins, hotels, and vacation rentals near Oslo Lake in St. Louis 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 Oslo Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 36 ft |
| Surface Area | 99 acres |
| Shoreline Length | 3.7 mi |
| Littoral Zone | 58% |
| 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 Oslo Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 2025-07-14 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Northern Pike | 5.67 | 1.61 lb |
| Yellow Perch | 0.25 | 0.09 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.
Northern Pike
Yellow Perch
From the 2025-07-14 survey
Oslo Lake is located approximately eight miles west of Kettle Falls, Minnesota. This 99.2-acre lake has a maximum depth of 36 feet and dark tannin-stained water. A fisheries survey was completed in Oslo Lake during the 2025 field season as part of a regular rotation of surveys in the International Falls Management…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Oslo Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OsloFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.006 m/yr | 5 |
| Phosphorus | ↓ Declining | +2.17 µg/L/yr | 4 |
EPA Impairment Status
Oslo Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MN69-0838-00 · Official waterbody report
Graded lakes near Oslo Lake
Oslo Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in St. Louis County
Frequently asked questions about Oslo Lake
What is the water quality grade for Oslo Lake?
- Oslo Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 9.2 ft visibility. Maximum depth: 36 ft. Surface area: 99.24 acres.
Is Oslo Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Oslo Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
How deep is Oslo Lake?
- Oslo Lake has a maximum depth of 36 feet. The lake covers 99.24 acres.
What fish are in Oslo Lake?
- Fish species found in Oslo Lake include northern pike, yellow perch. Oslo Lake is located in St. Louis County, Minnesota.
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Where this data comes from
1 measurement from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Minnesota Water Science Center
USGS-MN1 sample · 2023
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder