Fourth Lake
St. Louis County, Minnesota205 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Fourth Lake. Here is what has been measured.
- 20 ft max depth
- Limited data
Fourth Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.5 ft visibility. Maximum depth: 20 ft. Surface area: 204.9 acres.
Fourth Lake is a 205-acre lake in St. Louis County, Minnesota with a maximum depth of 20 feet. Overall water quality is declining over recent sampling years. The lake supports 13 documented fish species including black bullhead, black crappie, and bluegill. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-09. Methodology: how these readings are compared.
What Fourth Lake is good for
From access and monitoring records, not editorial picks.
- Fishing13 species recorded
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Fourth Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Fourth Lake
These are the measurements Minnesota PCA publishes for Fourth 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 1.5 ft of visibility. TSI 72.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading 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. | 72 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Fourth Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
20 ft
Surface area
205 acres
Shoreline
7.8 mi
Littoral zone
86%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
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Fish Species
Click a species to see every lake where it is documented.
Fishing Fourth Lake
Water Quality Trend: Worsening
Based on 4 years of monitoring (2021–2024).
Water clarity
Worsening4 years
Nearby Lakes in St. Louis County
Frequently asked questions about Fourth Lake
Where is Fourth Lake?
- Fourth Lake is a lake in St. Louis County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Fourth Lake?
- Fourth Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 1.5 ft visibility. Maximum depth: 20 ft. Surface area: 204.9 acres.
Is Fourth Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Fourth Lake?
- Fourth Lake has a maximum depth of 20 feet. The lake covers 204.9 acres.
What fish are in Fourth Lake?
- Fish species found in Fourth Lake include black bullhead, black crappie, bluegill, brown bullhead, channel catfish, northern pike, pumpkinseed, rock bass, shorthead redhorse, walleye, white sucker, yellow bullhead, yellow perch. Fourth Lake is located in St. Louis County, Minnesota.
Can I fish at Fourth Lake?
- Public access to Fourth Lake is listed as no on the lake record, so confirm before you make the trip. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
9 measurements from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA9 samples · 2024
Analytical methods
- Field measurement/observation, generic method
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
Lake details from Minnesota DNR LakeFinder