Upper Estuary Lake
Douglas County, WisconsinView mapDirections
Wisconsin DNR publishes the water-quality measurements for Upper Estuary Lake. Here is what has been measured.
- Eutrophic
- Public access
- Limited data
Upper Estuary Lake in Douglas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 52 µg/L. Chlorophyll-a (algae): 1.4 µg/L.
Upper Estuary Lake is a productive, nutrient-rich eutrophic lake in Douglas County, Wisconsin. Limited fish-species data available. Public access is available with 1 public boat landing. 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. Methodology: how these readings are compared.
What Upper Estuary Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyBacteria tested: exceedances
Based on clarity and algae readings from past sampling — there is no 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.
Whether Upper Estuary 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 Upper Estuary Lake
These are the measurements Wisconsin DNR publishes for Upper Estuary 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 2.1 ft of visibility. Phosphorus 52 µg/L. Chlorophyll-a 1.4 µg/L. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 52µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 1.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Upper Estuary Lake
Answers come straight from the public measurements and survey records on this page.
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.
Column height runs from this lake’s coldest month (63°F) to its warmest (77°F).
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
- Boyscout ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Upper Estuary Lake
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Top-rated places to stay near Upper Estuary Lake
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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.
Nearby Lakes in Douglas County
Frequently asked questions about Upper Estuary Lake
Where is Upper Estuary Lake?
- Upper Estuary 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 Upper Estuary Lake?
- Upper Estuary Lake in Douglas County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. 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 is a historical summary of past bacteria testing, not a current reading and not a swimming clearance. Bacteria levels can spike quickly after heavy rain, so whether Upper Estuary Lake is safe to swim in today is a call for Wisconsin's water agency and the county health department; check their current beach 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 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Boyscout Park. Public access is listed as yes.
Can I fish at Upper Estuary Lake?
- Upper Estuary Lake has 1 documented boat landing 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 Upper Estuary Lake across LakeQuality
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)
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