Upper Estuary Lake
Upper Estuary Lake in Douglas County, Wisconsin has a water quality grade of C (Fair). Water clarity: 2.1 ft visibility. Phosphorus: 52 µg/L. Chlorophyll-a (algae): 1.4 µg/L.
- Clarity
- 2.1 ft
- Typical in August
- 72°F
- Type
- Eutrophic
- Public access
- Yes
Next lake in Douglas County
Upper Estuary Lake is a productive, nutrient-rich eutrophic lake in Douglas County, Wisconsin. Water quality is graded C based on 2 sampling years through 2025. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 14 other monitored lakes in Douglas County, Upper Estuary Lake ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria D
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Based on E. coli testing, Upper Estuary Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 15.4% of 13 samples across 2 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Wisconsin’s current beach and health-department advisories before swimming.
Water Quality Grade: C (Fair)
Very murky, less than 2.1 ft of visibility. Phosphorus level: 52 µg/L. Chlorophyll-a: 1.4 µg/L. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.1 ft | Not graded |
| Phosphorus | 52 µg/L | Poor |
| Chlorophyll-a (Algae) | 1.4 µg/L | Good |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Upper Estuary Lake
Compare lakeside cabins, hotels, and vacation rentals near Upper Estuary 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 Upper Estuary Lake
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Water Temperature
Upper Estuary Lake typically sits around 72°F at the surface in August. Summer average is about 72°F. Usually warmest in Jul (about 77°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2025–2025) via the EPA Water Quality Portal. See the full Upper Estuary Lake water temperature breakdown →
Recreation & Access
- Sajac Memorial ParkPublic
- Boyscout ParkPublic
Fishing Upper Estuary Lake
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Upper Estuary Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Radio Tower Bay RestorationDuluth · 1 mi away · NPDES MN0070611Recent violation
- Me Global IncDuluth · 0.9 mi away · NPDES MN0053830
- Mud Lake SiteDuluth · 1.3 mi away · NPDES MN0072320
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.
County Ranking
Ranked #12 of 15 lakes in Douglas County
Nearby Lakes in Douglas County
Frequently asked questions about Upper Estuary Lake
What is the water quality grade for Upper Estuary Lake?
- Upper Estuary Lake in Douglas County, Wisconsin has a water quality grade of C (Fair). Water clarity: 2.1 ft visibility. Phosphorus: 52 µg/L. Chlorophyll-a (algae): 1.4 µg/L.
Is Upper Estuary Lake safe to swim in?
- Based on E. coli testing, Upper Estuary Lake frequently exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 15.4% of 13 samples across 2 seasons. That works out to a bacteria swim-safety grade of D — a historical summary of past testing, not a current reading. Upper Estuary Lake has a water quality grade of C (Fair). Bacteria levels can spike quickly after heavy rain, so always check Wisconsin's current beach and health-department advisories before you swim.
What is the water temperature of Upper Estuary Lake?
- Upper Estuary Lake typically sits around 72°F at the surface in August, from 9 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 Upper Estuary Lake?
- Upper Estuary Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Sajac Memorial Park, Boyscout Park. Public access is listed as yes.
Explore Upper Estuary Lake across LakeGrade
9.5 mi away · 165 ft
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Where this data comes from
27 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
MNPCA27 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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
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