Superior Lake
Superior Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 10 µg/L.
- Typical in August
- 60°F
- Mean depth
- ~481 ft est.
- Public access
- Yes
Next lake in St. Louis County
Why Superior 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 Superior Lake, no EPA ecoregion for this lake, so the National Lakes Assessment condition thresholds cannot be applied. Sampling here has recorded phosphorus, but not water clarity 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.
Superior Lake is a lake in St. Louis County, Minnesota with an estimated average depth of about 481 feet. Limited fish-species data available. Public access is available.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-10-11. 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 Superior Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
No clarity data. Phosphorus level: 10 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 10 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Superior Lake
Compare lakeside cabins, hotels, and vacation rentals near Superior 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 Superior Lake
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Water Temperature
Superior Lake typically sits around 60°F at the surface in August. Summer average is about 57°F. Usually warmest in Sep (about 63°F) and coldest in May (about 46°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 18 field readings (2022–2022) via the EPA Water Quality Portal. See the full Superior Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~481 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Superior Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Superior Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Superior Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fish Stocking History — SuperiorFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — SuperiorPublic Water Access Sites · MN DNR LakeFinder
Nearby Lakes in St. Louis County
Frequently asked questions about Superior Lake
What is the water quality grade for Superior Lake?
- Superior Lake in St. Louis County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 10 µg/L.
Is Superior Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Superior Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Superior Lake?
- Superior Lake typically sits around 60°F at the surface in August, from 18 EPA Water Quality Portal field readings (2022–2022). That is a typical value for the month, not a live reading.
How deep is Superior Lake?
- No published bathymetric survey covers Superior Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 481 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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Where this data comes from
108 measurements from 3 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA108 samples · 2022
Analytical methods
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (3)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder