Bull Frog Lake
Cook County, IllinoisView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Algal growth
- Limited data
Bull Frog Lake in Cook County, Illinois is not rated for water quality — its monitoring record does not meet the evidence bar.
- Typical in September
- 65°F
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Watch Bull Frog Lake’s letter
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Why Bull Frog Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Bull Frog Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by Illinois EPA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Bull Frog Lake is a lake in Cook County, Illinois.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-03-21. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Bull Frog 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.
Water quality measurements for Bull Frog Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples |
Water Temperature
Bull Frog Lake typically sits around 65°F at the surface in September. Summer average is about 76°F. Usually warmest in Aug (about 79°F) and coldest in Oct (about 60°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 45 field readings (2010–2022) via the EPA Water Quality Portal. See the full Bull Frog Lake water temperature breakdown →
Fishing Bull Frog Lake
Reservoir Info (USACE NID)
Bull Frog 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
Bull Frog Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IL_RHZF · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Bull Frog Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Rowell Chemical CorporationWillow Springs · 0.7 mi away · NPDES IL0066613Recent violation
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.
Graded lakes near Bull Frog Lake
Bull Frog Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Cook County
Frequently asked questions about Bull Frog Lake
Where is Bull Frog Lake?
- Bull Frog Lake is a lake in Cook County, Illinois. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Bull Frog Lake?
- Bull Frog Lake in Cook County, Illinois is not rated for water quality — its monitoring record does not meet the evidence bar.
Is Bull Frog Lake safe to swim in?
- The letter is not a swimming clearance. Bull Frog 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 Bull Frog Lake?
- Bull Frog Lake typically sits around 65°F at the surface in September, from 45 EPA Water Quality Portal field readings (2010–2022). That is a typical value for the month, not a live reading.
Explore Bull Frog Lake across LakeQuality
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Where this data comes from
1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Illinois Water Science Center
USGS-IL1 sample · 2022
Analytical methods
- Secchi disk method
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)