St. Louis Bay Lake
St. Louis Bay Lake in Douglas County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.3 ft visibility. Phosphorus: 70.5 µg/L. Chlorophyll-a (algae): 1.8 µg/L.
- Clarity
- 1.3 ft
- Public access
- Yes
Next lake in Douglas County
Why St. Louis Bay 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 St. Louis Bay Lake, no EPA ecoregion for this lake, so the National Lakes Assessment condition thresholds cannot be applied. Sampling here has recorded water clarity, 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.
St. Louis Bay Lake is a lake in Douglas County, Minnesota. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-22. 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 St. Louis Bay Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 1.3 ft of visibility. Phosphorus level: 70.5 µg/L. Chlorophyll-a: 1.8 µg/L. Trophic State Index: 58.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.3 ft | Not graded |
| Phosphorus | 70.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 1.8 µg/L | Not graded |
| Trophic State Index (TSI) | 58 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near St. Louis Bay Lake
Compare lakeside cabins, hotels, and vacation rentals near St. Louis Bay Lake in Douglas 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 St. Louis Bay Lake
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Recreation & Access
- Billings ParkPublic
- Arrowhead Bridge Fishing PierPublic
Fishing St. Louis Bay 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.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
Reservoir Info (USACE NID)
St. Louis Bay Lake is a man-made reservoir impounded by the Erie Pier Dike (completed 1978), built primarily for other on the Lake Superior; earth-type dam, 11 ft tall and 3,500 ft long.
- Normal storage
- 490 ac-ft
- Max storage
- 800 ac-ft
- Drainage area
- 0.14 sq mi
- Hazard class
- Low
- Owner
- Duluth Port Authority
Source: USACE National Inventory of Dams, NID ID MN00719 · Operator website · Matched by proximity (0.79 km)
EPA Impairment Status
St. Louis Bay 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 MN69-1291-02 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of St. Louis Bay Lake under Clean Water Act (NPDES) discharge permits.
- Minnesota Power - Hibbard Renewable Energy CenterDuluth · 0.9 mi away · NPDES MN0001015
- Dmirr Co-Duluth Ore DockDuluth · 1 mi away · NPDES MN0053384
- 40TH Avenue West - Saint Louis River EstuaryDuluth · 1.2 mi away · NPDES MN0071226
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Graded lakes near St. Louis Bay Lake
St. Louis Bay Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Douglas County
Frequently asked questions about St. Louis Bay Lake
What is the water quality grade for St. Louis Bay Lake?
- St. Louis Bay Lake in Douglas County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.3 ft visibility. Phosphorus: 70.5 µg/L. Chlorophyll-a (algae): 1.8 µg/L.
Is St. Louis Bay Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. St. Louis Bay Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 1.8 µg/L. Always check local health department advisories before swimming.
Are there boat ramps on St. Louis Bay Lake?
- St. Louis Bay Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Billings Park, Arrowhead Bridge Fishing Pier. Public access is listed as yes.
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Where this data comes from
57 measurements from 2 monitoring stations, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA57 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory