Bullfrog Lake
Cook County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Bullfrog Lake. Here is what has been measured.
- Hypereutrophic
- Impaired · Algal growth
- Limited data
Bullfrog Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.4 ft visibility. Phosphorus: 73 µg/L. Chlorophyll-a (algae): 124.5 µg/L.
Bullfrog Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, Illinois. Compared to the 15 other monitored lakes in Cook County, Bullfrog Lake ranks #13 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2020-10-13. Methodology: how these readings are compared.
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. Bullfrog Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, noxious aquatic plants, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
Whether Bullfrog 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 Bullfrog Lake
These are the measurements Illinois EPA publishes for Bullfrog 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 1.4 ft of visibility. Phosphorus 73 µg/L. Chlorophyll-a 124.5 µg/L. TSI 72.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 73µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 125µg/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. | 72 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Bullfrog Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Bullfrog Lake typically sits around 60°F at the surface in October. Summer average is about 78°F. Usually warmest in Aug (about 81°F) and coldest in Oct (about 60°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (60°F) to its warmest (81°F).
Typical surface water temperature by month, from 29 field readings (2010–2023) via the EPA Water Quality Portal. See the full Bullfrog Lake water temperature breakdown →
Stays via Stay22
Stays near Bullfrog Lake
Compare lakeside cabins, hotels, and vacation rentals near Bullfrog 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 Bullfrog Lake are listed below.
Top-rated places to stay near Bullfrog Lake
Prices for Oct 23–25, 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 Bullfrog Lake
Reservoir Info (USACE NID)
Bullfrog Lake is a man-made reservoir impounded by the Bullfrog Lake Dam (completed 1958), built primarily for recreation on the TRIB DES PLAINES RIVER; earth-type dam, 17 ft tall and 700 ft long.
- Normal storage
- 77 ac-ft
- Max storage
- 144 ac-ft
- Hazard class
- Significant
- Owner
- FOREST PRESERVE DISTRICT OF COOK COUNTY
Source: USACE National Inventory of Dams, NID ID IL00869 · Operator website
EPA Impairment Status
Bullfrog 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: Other.
Source: EPA ATTAINS assessment unit IL_RHZF · Official waterbody report
Nearby Lakes in Cook County
Frequently asked questions about Bullfrog Lake
Where is Bullfrog Lake?
- Bullfrog 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 Bullfrog Lake?
- Bullfrog Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1.4 ft visibility. Phosphorus: 73 µg/L. Chlorophyll-a (algae): 124.5 µg/L.
Is Bullfrog Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Bullfrog Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, noxious aquatic plants, nutrients (phosphorus, nitrogen), turbidity. Check local advisories before you swim.
What is the water temperature of Bullfrog Lake?
- Bullfrog Lake typically sits around 60°F at the surface in October, from 29 EPA Water Quality Portal field readings (2010–2023). That is a typical value for the month, not a live reading.
Explore Bullfrog Lake across LakeQuality
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Where this data comes from
32 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_WQX32 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