Arrowhead Lake
Cook County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Arrowhead Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Cause unknown
- Public access
- Limited data
Arrowhead Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 38 µg/L. Chlorophyll-a (algae): 37.6 µg/L.
Arrowhead Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, Illinois. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 15 other monitored lakes in Cook County, Arrowhead Lake ranks #12 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2020-10-05. Methodology: how these readings are compared.
For a place on the water, look through cabin and lake-house rentals near Arrowhead Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
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. Arrowhead Lake is listed impaired under Clean Water Act §303(d) (IR 5) for cause unknown, mercury. Check local advisories before you swim.
Whether Arrowhead Lake is safe to swim in today is a call for the Illinois Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Arrowhead Lake
These are the measurements Illinois EPA publishes for Arrowhead 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 38 µg/L. Chlorophyll-a 37.6 µg/L. TSI 63.
| 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 | 38µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 37.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 63 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Arrowhead Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Arrowhead Lake typically sits around 61°F at the surface in October. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (56°F) to its warmest (78°F).
Typical surface water temperature by month, from 112 field readings (2011–2022) via the EPA Water Quality Portal. See the full Arrowhead Lake water temperature breakdown →
Stays via Stay22
Stays near Arrowhead Lake
Compare lakeside cabins, hotels, and vacation rentals near Arrowhead Lake in Cook County, Illinois — 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Arrowhead Lake are listed below.
Top-rated places to stay near Arrowhead Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
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Planning a whole trip? See where to stay at Illinois’s top lakes →
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Fishing Arrowhead Lake
Water quality readings over time
2 seasons of samples on record (2020–2021). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Improving-11 µg/L/yr2 years
Chlorophyll-a
Improving-13.2 µg/L/yr2 years
EPA Impairment Status
Arrowhead 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, Other.
Source: EPA ATTAINS assessment unit IL_RHZE · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Arrowhead Lake under Clean Water Act (NPDES) discharge permits.
- West Shore Pipe Line Co-AlsipAlsip · 2.2 mi away · NPDES IL0077518
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 Cook County
Frequently asked questions about Arrowhead Lake
Where is Arrowhead Lake?
- Arrowhead Lake is a lake in Cook County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Arrowhead Lake?
- Arrowhead Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 2.1 ft visibility. Phosphorus: 38 µg/L. Chlorophyll-a (algae): 37.6 µg/L.
Is Arrowhead Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Arrowhead Lake is listed impaired under Clean Water Act §303(d) (IR 5) for cause unknown, mercury. Check local advisories before you swim.
What is the water temperature of Arrowhead Lake?
- Arrowhead Lake typically sits around 61°F at the surface in October, from 112 EPA Water Quality Portal field readings (2011–2022). That is a typical value for the month, not a live reading.
Can I fish at Arrowhead Lake?
- Public access to Arrowhead Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Illinois's fish and wildlife agency, so check its current regulations before you go.
Explore Arrowhead Lake across LakeQuality
Planning a trip around Indiana Dunes?
Arrowhead Lake is about 36 miles from Indiana Dunes National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Indiana Dunes →More lakes in Illinois
Other Lakes in Illinois
Hypereutrophic Lakes in Illinois
Where this data comes from
36 measurements from 2 monitoring stations, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX36 samples · 2020
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (2)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)