Bullfrog Lake Dam
Bullfrog Lake Dam is an earth dam located in Cook County, Illinois, built in 1958. It carries a Significant hazard potential classification.
About Bullfrog Lake Dam
The primary purpose of Bullfrog Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Forest Preserve District Of Cook County (local government). It impounds the Trib Des Plaines River near Lemont.
The dam stands 17 feet tall and stretches 700 feet across, and has a maximum storage capacity of 144 acre-feet. Completed in 1958, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. The most recent inspection on record was 12/22/2025.
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Location
| State | Illinois |
| County | Cook |
| Nearest City | Lemont |
| River/Stream | Trib Des Plaines River |
| Coordinates | 41.71069, -87.89985 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 17 ft |
| Dam Height | 17 ft |
| Dam Length | 700 ft |
| Year Completed | 1958 (68 years old) |
Storage & Hydraulics
| NID Storage | 144 acre-ft |
| Max Storage | 144 acre-ft |
| Normal Storage | 77 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | FOREST PRESERVE DISTRICT OF COOK COUNTY |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 12/22/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00869 |
| Federal ID | IL00869 |
| More Info | State Dam Safety Program |