Otto Lake
St. Louis County, Minnesota154 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Otto Lake. Here is what has been measured.
- Impaired · Mercury
- 27 ft max depth
- Public access
- Limited data
Otto Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6 ft visibility. Maximum depth: 27 ft. Surface area: 154.07 acres.
Minnesota DNR's Standard Survey on August 9, 1999 caught 2.50 northern pike per gill net at Otto Lake. Length samples in the latest survey that recorded them ran 19–28 inches. DNR survey details →
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. Methodology: how these readings are compared.
What Otto Lake is good for
From access and monitoring records, not editorial picks.
- Fishing5 species recorded
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Otto Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Otto Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Otto Lake
These are the measurements Minnesota PCA publishes for Otto Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 6 ft. TSI 51.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 51 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Otto Lake
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on August 9, 1999 caught 2.50 northern pike per gill net at Otto Lake. Length samples in the latest survey that recorded them ran 19–28 inches.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Otto Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
1 survey on file from MN DNR Fisheries. Most recent: 1999-08-09 (Standard Survey).
1 survey on file · most recent 1999-08-09 (Standard Survey)
27 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Yellow Perch | 3.39 | 1–9 in 1999-08-09 | 0.13 lb |
| Northern Pike | 2.50 | 19–28 in 1999-08-09 | 3.49 lb |
| Golden Shiner | 1.70 | 5–6 in 1999-08-09 | 0.13 lb |
| Smallmouth Bass | 1.63 | 2–15 in 1999-08-09 | 0.44 lb |
| Pumpkinseed | 1.11 | 3–4 in 1999-08-09 | 0.13 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and is not a weekly bite report.
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
Golden Shiner
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
Lake Details
Max depth
27 ft
Average depth
10 ft
Surface area
154 acres
Shoreline
3.2 mi
Littoral zone
71%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,614 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays 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
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Follow Otto Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Otto Lake
Water Quality Trend: Improving
Based on 4 years of monitoring (2021–2025).
Water clarity
Improving4 years
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
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MN69-0144-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Otto Lake
Where is Otto Lake?
- Otto Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Otto Lake?
- Otto Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 6 ft visibility. Maximum depth: 27 ft. Surface area: 154.07 acres.
Is Otto Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Otto Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
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.
What did the DNR fisheries survey find at Otto Lake?
- Minnesota DNR's Standard Survey on August 9, 1999 caught 2.50 northern pike per gill net at Otto Lake. Length samples in the latest survey that recorded them ran 19–28 inches. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Otto Lake’s water-quality measurements separately, and the water-quality trend over 4 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Otto Lake?
- Public access to Otto Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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