Iron Lake
St. Louis County, Minnesota1,962 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Iron Lake. Here is what has been measured.
- Impaired · Mercury
- spiny waterflea
- 64 ft max depth
- Limited data
Iron Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5 ft visibility. Maximum depth: 64 ft. Surface area: 1961.99 acres.
Iron Lake is a 1,962-acre lake in St. Louis County, Minnesota with a maximum depth of 64 feet. The lake supports 9 documented fish species including black crappie, cisco species, and lake whitefish. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-07-06. Methodology: how these readings are compared.
What Iron Lake is good for
From access and monitoring records, not editorial picks.
- Fishing9 species recorded
- Deep water64 ft surveyed max depth
- Big water1,962 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Iron Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Iron 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 Iron Lake
These are the measurements Minnesota PCA publishes for Iron Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5 ft. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 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. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Iron Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
64 ft
Surface area
1,962 acres
Shoreline
53.5 mi
Public access
No
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
2,991 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,211 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
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Stays near Iron Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Iron Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
EPA Impairment Status
Iron Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit MN69-0121-00 · Official waterbody report
Nearby Lakes in St. Louis County
Frequently asked questions about Iron Lake
Where is Iron Lake?
- Iron 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 Iron Lake?
- Iron Lake in St. Louis County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 5 ft visibility. Maximum depth: 64 ft. Surface area: 1961.99 acres.
Is Iron Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Iron Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
How deep is Iron Lake?
- Iron Lake has a maximum depth of 64 feet. The lake covers 1961.99 acres.
What fish are in Iron Lake?
- Fish species found in Iron Lake include black crappie, cisco species, lake whitefish, northern pike, rock bass, sauger, walleye, white sucker, yellow perch. Iron Lake is located in St. Louis County, Minnesota.
Can I fish at Iron Lake?
- Public access to Iron 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
1 measurement 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
MNPCA1 sample · 2025
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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder