Oyster Lake
Oyster Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.6 ft visibility. Maximum depth: 130 ft. Surface area: 762.91 acres.
- Clarity
- 6.6 ft
- Max depth
- 130 ft
- Area
- 763 acres
- Trend
- ↓ Declining
- Public access
- No
Next lake in St. Louis County
Why Oyster 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 Oyster 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.
Oyster Lake is a 763-acre lake in St. Louis County, Minnesota with a maximum depth of 130 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-26. Grade methodology: LakeGrade methodology.
Watch Oyster Lake water quality
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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 Oyster Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 6.6 ft. Trophic State Index: 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Oyster Lake
Compare lakeside cabins, hotels, and vacation rentals near Oyster 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 Oyster Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 130 ft |
| Surface Area | 763 acres |
| Shoreline Length | 8.7 mi |
| Littoral Zone | 31% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fishing Oyster Lake
DNR Fisheries Survey Summary
4 surveys on file from MN DNR Fisheries. Most recent: 2025-07-29 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Rock Bass | 3.50 | 0.21 lb |
| White Sucker | 2.22 | 2.03 lb |
| Tullibee (Cisco) | 1.79 | 0.13 lb |
| BUB | 1.61 | 1.96 lb |
| Lake Trout | 1.25 | 2.31 lb |
| Northern Pike | 0.71 | 4.37 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.
Rock Bass
White Sucker
Tullibee (Cisco)
BUB
From the 2025-07-29 survey
Temperature and dissolved oxygen (DO) measurements were collected from the deepest basin in Oyster Lake on July 29th, 2025, to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Lake Trout, the most sensitive coldwater species present in this lake (Cisco, also known as…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Oyster Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OysterFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.093 m/yr | 2 |
EPA Impairment Status
Oyster 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 MN69-0330-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Oyster Lake
What is the water quality grade for Oyster Lake?
- Oyster Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.6 ft visibility. Maximum depth: 130 ft. Surface area: 762.91 acres.
Is Oyster Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Oyster 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 Oyster Lake?
- Oyster Lake has a maximum depth of 130 feet. The lake covers 762.91 acres.
Explore Oyster Lake across LakeGrade
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Where this data comes from
2 measurements from 1 monitoring station, 2022–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA2 samples · 2022–2025
Analytical methods
- Field measurement/observation, generic method
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