Iron Lake
Cook County, Minnesota122 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Iron Lake. Here is what has been measured.
- Mesotrophic
- Impaired · Mercury
- 19 ft max depth
- Public access
- Limited data
Iron Lake in Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.9 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 19 ft. Surface area: 122.27 acres.
Iron Lake is a 122-acre mesotrophic lake in Cook County, Minnesota with a maximum depth of 19 feet. Overall water quality is declining over recent sampling years. The lake supports 8 documented fish species including bluegill, green sunfish, and northern pike. Public access is available. Compared to the 43 other monitored lakes in Cook County, Iron Lake ranks #35 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Methodology: how these readings are compared.
Iron Lake covers about 120 acres in Cook County. Vrbo is where to look for cabins and lake homes around Iron Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Iron Lake is good for
From access and monitoring records, not editorial picks.
- Fishing8 species recorded
Swimming conditions
Readings onlyLimited data
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.
Nutrient and algae readings are not a swimming clearance. Iron Lake is listed impaired under Clean Water Act §303(d) (IR 4A) 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 4.9 ft. Phosphorus 18 µg/L. Chlorophyll-a 5.8 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 18µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 5.8µg/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. | 49 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Iron Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Iron Lake typically sits around 63°F at the surface in September. Summer average is about 68°F. Usually warmest in Jul (about 69°F) and coldest in May (about 53°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (53°F) to its warmest (69°F).
Typical surface water temperature by month, from 48 field readings (2011–2025) via the EPA Water Quality Portal. See the full Iron Lake water temperature breakdown →
Lake Details
Max depth
19 ft
Surface area
122 acres
Shoreline
7.2 mi
Littoral zone
60%
Share shallower than 15 ft
Public access
Yes
Listed by Minnesota PCA
Lake Size & Watershed
Watershed (drainage) area
4 sq mi
HydroLAKES / HydroSHEDS
Elevation
1,857 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Stays via Stay22
Stays near Iron Lake
Compare lakeside cabins, hotels, and vacation rentals near Iron Lake in Cook 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.
Top-rated places to stay near Iron Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Follow Iron Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Iron Lake
Water quality readings over time
2 seasons of samples on record (2020–2025). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Worsening2 years
Phosphorus
Worsening+1.7 µg/L/yr2 years
Chlorophyll-a
Worsening+0.5 µg/L/yr2 years
EPA Impairment Status
Iron Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN16-0328-00 · Official waterbody report
Nearby Lakes in Cook County
Frequently asked questions about Iron Lake
Where is Iron Lake?
- Iron Lake is a lake in Cook 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 Cook County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.9 ft visibility. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 5.8 µg/L. Maximum depth: 19 ft. Surface area: 122.27 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 4A) for mercury. Check local advisories before you swim.
What is the water temperature of Iron Lake?
- Iron Lake typically sits around 63°F at the surface in September, from 48 EPA Water Quality Portal field readings (2011–2025). That is a typical value for the month, not a live reading.
How deep is Iron Lake?
- Iron Lake has a maximum depth of 19 feet. The lake covers 122.27 acres.
What fish are in Iron Lake?
- Fish species found in Iron Lake include bluegill, green sunfish, northern pike, rock bass, splake, walleye, white sucker, yellow perch. Iron Lake is located in Cook County, Minnesota.
Can I fish at Iron Lake?
- Public access to Iron Lake is listed as yes on the lake record. 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.
Explore Iron Lake across LakeQuality
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Where this data comes from
13 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
MNPCA13 samples · 2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent 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
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder