Marseilles Lock And Dam
Marseilles Lock And Dam is a concrete dam located in LaSalle County, Illinois, built in 1933. It carries a Significant hazard potential classification.
About Marseilles Lock And Dam
The primary purpose of Marseilles Lock And Dam is navigation. The dam maintains water levels sufficient for boat and barge traffic, supporting commercial or recreational navigation on the waterway. The dam is owned by Usace - Rock Island District (federal). It impounds the Illinois River near Ottawa.
The dam stands 58 feet tall and stretches 2,078 feet across, has a maximum storage capacity of 14,000 acre-feet, and collects water from a drainage area of 8,259 square miles. Completed in 1933, the structure is well-established, with more than 75 years of service.
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. An emergency action plan is in place for this dam. The most recent inspection on record was 06/21/2023.
At 58 feet, this dam is taller than 95% of all dams in the United States.
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Location
| State | Illinois |
| County | LaSalle |
| Nearest City | Ottawa |
| River/Stream | Illinois River |
| Coordinates | 41.32296, -88.70856 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 58 ft |
| Dam Length | 2,078 ft |
| Year Completed | 1933 (93 years old) |
Storage & Hydraulics
| NID Storage | 14,000 acre-ft |
| Max Storage | 14,000 acre-ft |
| Drainage Area | 8,259 sq mi |
| Max Discharge | 137,000 cfs |
| Spillway Type | None |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - Rock Island District |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not Available |
| Last Inspection | 06/21/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00003 |
| Federal ID | IL00003 |
| More Info | State Dam Safety Program |