Upper Estuary Lake
Upper Estuary Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 1.9 ft visibility. Phosphorus: 49.5 µg/L. Chlorophyll-a (algae): 1.7 µg/L. Maximum depth: 55 ft. Surface area: 10255.25 acres.
- Clarity
- 1.9 ft
- Max depth
- 55 ft
- Area
- 10,255 acres
- Type
- Eutrophic
- Public access
- Yes
Next lake in St. Louis County
Upper Estuary Lake is a 10,255-acre productive, nutrient-rich eutrophic lake in St. Louis County, Minnesota with a maximum depth of 55 feet. Water quality is graded C based on 2 sampling years through 2025. The lake supports 33 documented fish species including American eel, black bullhead, and black crappie. Public access is available with 1 public boat landing. Compared to the 67 other monitored lakes in St. Louis County, Upper Estuary Lake ranks #62 for water quality.
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
Grade onlyLimited data
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 1.9 ft of visibility. Phosphorus level: 49.5 µg/L. Chlorophyll-a: 1.7 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.9 ft | Not graded |
| Phosphorus | 49.5 µg/L | Poor |
| Chlorophyll-a (Algae) | 1.7 µg/L | Good |
| Trophic State Index (TSI) | 55 | 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 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 55 ft |
| Surface Area | 10,255 acres |
| Shoreline Length | 195.5 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Recreation & Access
- Fond du Lac CampgroundPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Upper Estuary Lake
EPA Impairment Status
Upper Estuary 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 MN69-1291-04 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Upper Estuary Lake under Clean Water Act (NPDES) discharge permits.
- Murphy Oil Usa IncEsko · 4.1 mi away · NPDES MN0041556
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 #62 of 68 lakes in St. Louis County
Nearby Lakes in St. Louis County
Frequently asked questions about Upper Estuary Lake
What is the water quality grade for Upper Estuary Lake?
- Upper Estuary Lake in St. Louis County, Minnesota has a water quality grade of C (Fair). Water clarity: 1.9 ft visibility. Phosphorus: 49.5 µg/L. Chlorophyll-a (algae): 1.7 µg/L. Maximum depth: 55 ft. Surface area: 10255.25 acres.
Is Upper Estuary Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Upper Estuary Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 1.7 µg/L. Always check local health department advisories before swimming.
How deep is Upper Estuary Lake?
- Upper Estuary Lake has a maximum depth of 55 feet. The lake covers 10255.25 acres.
What fish are in Upper Estuary Lake?
- Fish species found in Upper Estuary Lake include American eel, black bullhead, black crappie, bluegill, brook trout, brown bullhead, brown trout, burbot, channel catfish, common carp, freshwater drum, gizzard shad, lake sturgeon, largemouth bass, longnose sucker, muskellunge, northern pike, pumpkinseed, quillback, rainbow smelt, rainbow trout, rock bass, shorthead redhorse, silver redhorse, smallmouth bass, splake, tiger muskellunge, walleye, white bass, white perch, white sucker, yellow bullhead, yellow perch. Upper Estuary Lake is located in St. Louis County, Minnesota.
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 Fond du Lac Campground. Public access is listed as yes.
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Where this data comes from
43 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
MNPCA43 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 details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory