Tampier Lake Dam is a gravity dam located in Cook County, Illinois, built in 1964. It carries a Significant hazard potential classification.
Dam profile
NID height · 9 ft9 ft tall and 240 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Tampier Lake Dam
The primary purpose of Tampier 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 Long Run Creek near Lemont-offstream.
The dam stands 9 feet tall and stretches 240 feet across, and has a maximum storage capacity of 859 acre-feet. Completed in 1964, 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-offstream |
| River/Stream | Trib Long Run Creek |
| Coordinates | 41.64588, -87.90774 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 9 ft |
| Dam Height | 9 ft |
| Dam Length | 240 ft |
| Year Completed | 1964 (62 years old) |
Storage & Hydraulics
| NID Storage | 859 acre-ft |
| Max Storage | 859 acre-ft |
| Normal Storage | 668 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 assessed |
| Last Inspection | 12/22/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00866 |
| Federal ID | IL00866 |
| More Info | State Dam Safety Program |