Otto Lake
Otto Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6 ft visibility. Maximum depth: 27 ft. Surface area: 154.07 acres.
- Clarity
- 6 ft
- Max depth
- 27 ft
- Area
- 154 acres
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in St. Louis County
Why Otto 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 Otto Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. 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.
Otto Lake is a 154-acre lake in St. Louis County, Minnesota with a maximum depth of 27 feet (10-foot average). Overall water quality is improving over recent sampling years. The lake supports 5 documented fish species including northern pike, pumpkinseed, and smallmouth bass. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-06-14. Grade methodology: LakeGrade methodology.
Watch Otto Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Otto Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 6 ft. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Otto Lake
Compare lakeside cabins, hotels, and vacation rentals near Otto 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 Otto Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 27 ft |
| Average Depth | 10 ft |
| Surface Area | 154 acres |
| Shoreline Length | 3.2 mi |
| Littoral Zone | 71% |
| Public Access | Yes |
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 Otto Lake
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1999-08-09 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Yellow Perch | 3.39 | 0.13 lb |
| Northern Pike | 2.50 | 3.49 lb |
| GOS | 1.70 | 0.13 lb |
| Smallmouth Bass | 1.63 | 0.44 lb |
| Pumpkinseed | 1.11 | 0.13 lb |
| BNS | 0.67 | — |
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.
Yellow Perch
Northern Pike
GOS
Smallmouth Bass
From the 1999-08-09 survey
Otto Lake is a softwater lake located in the Superior National Forest, 4 miles south of Fairbanks. Due to unsuccessful walleye stocking, primary management has shifted from walleye to smallmouth bass. The primary purpose of the 1999 assessment was to evaluate adult smallmouth bass stocking in 1995 and 1997. Results…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Otto Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OttoFisheries Lake Survey · MN DNR LakeFinder
- —Public Water Access Sites — OttoPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.663 m/yr | 4 |
EPA Impairment Status
Otto 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 MN69-0144-00 · Official waterbody report
Graded lakes near Otto Lake
Otto Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in St. Louis County
Frequently asked questions about Otto Lake
What is the water quality grade for Otto Lake?
- Otto Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6 ft visibility. Maximum depth: 27 ft. Surface area: 154.07 acres.
Is Otto Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Otto 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 Otto Lake?
- Otto Lake has a maximum depth of 27 feet and an average depth of 10 feet. The lake covers 154.07 acres.
What fish are in Otto Lake?
- Fish species found in Otto Lake include northern pike, pumpkinseed, smallmouth bass, white sucker, yellow perch. Otto Lake is located in St. Louis County, Minnesota.
Explore Otto Lake across LakeGrade
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in St. Louis County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Lake Vermilion Area area
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Lakes in the Rainy Lake Watershed, ranked by water quality
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
Other Lakes in Minnesota
Eutrophic Lakes in Minnesota
Where this data comes from
10 measurements from 1 monitoring station, 2021–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA10 samples · 2021–2025
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