Duluth Lake
Douglas County, WisconsinView mapDirections
Wisconsin DNR publishes the water-quality measurements for Duluth Lake. Here is what has been measured.
- Public access
- Limited data
Duluth Lake in Douglas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 54 µg/L. Chlorophyll-a (algae): 2.9 µg/L.
Duluth Lake is a lake in Douglas County, Wisconsin. Limited fish-species data available. Public access is available with 3 public boat landings.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-22. Methodology: how these readings are compared.
What Duluth Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch3 documented ramps
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Duluth Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Duluth Lake
These are the measurements Wisconsin DNR publishes for Duluth Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1.6 ft of visibility. Phosphorus 54 µg/L. Chlorophyll-a 2.9 µg/L. TSI 58.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 54µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 2.9µg/L | Measured, not scored 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. | 58 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Duluth Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Duluth Lake typically sits around 58°F at the surface in September. Summer average is about 65°F. Usually warmest in Jul (about 70°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (56°F) to its warmest (70°F).
Typical surface water temperature by month, from 72 field readings (2025–2025) via the EPA Water Quality Portal. See the full Duluth Lake water temperature breakdown →
Recreation & Access
- Barkers Island MarinaPublic
- Loons FootPublic
- Park PointPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Duluth Lake
Compare lakeside cabins, hotels, and vacation rentals near Duluth Lake in Douglas County, Wisconsin — 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 Duluth Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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 trip? Cabins and lodging at Duluth Lake → · more Wisconsin lake trips
Follow Duluth Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Duluth Lake
Regulated Pollution Sources Nearby
7 EPA-permitted facilities operate within about 5 miles of Duluth Lake under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 2 facilities have a reported Clean Water Act violation in the past three years.
- Superior Sewage Disposal SystemSuperior · 0.6 mi away · NPDES WI0025593MajorRecent violation
- Calumet Superior LlcSuperior · 2.9 mi away · NPDES WI0003085Major
- Duluth Coastal Infrastructure Dredging ProjectDuluth · 0.8 mi away · NPDES MN0072052Recent violation
- Enbridge Pipelines LlcSuperior · 1.4 mi away · NPDES MN0069175
- Duluth Winnipeg Pacific Rwy SwSuperior · 2.9 mi away · NPDES WI0044831
- Midwest Energy Resources CompanySuperior · 2.9 mi away · NPDES WI0038946
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.
Nearby Lakes in Douglas County
Frequently asked questions about Duluth Lake
Where is Duluth Lake?
- Duluth Lake is a lake in Douglas County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Duluth Lake?
- Duluth Lake in Douglas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 1.6 ft visibility. Phosphorus: 54 µg/L. Chlorophyll-a (algae): 2.9 µg/L.
Is Duluth Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Duluth Lake?
- Duluth Lake typically sits around 58°F at the surface in September, from 72 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
Are there boat ramps on Duluth Lake?
- Duluth Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Barkers Island Marina, Loons Foot, Park Point. Public access is listed as yes.
Can I fish at Duluth Lake?
- Duluth Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Duluth Lake across LakeQuality
2 documented falls within 11.5 mi, nearest Upper Falls (Amnicon Falls State Park)
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Douglas County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Lakes in the Lake Superior Basin (MN+WI), ranked by water quality
Wisconsin's cleanest lakes, ranked on agency measurements
More lakes in Wisconsin
State Parks Near Duluth Lake
Other Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Where this data comes from
30 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA30 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory