Mississippi River Lock and Dam 11 is a concrete dam located in Dubuque County, Iowa, built in 1937. It carries a Significant hazard potential classification.
Dam profile
NID height · 43 ft43 ft tall and 5,130 ft long, taller than 89% of U.S. dams with a recorded height. 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 Mississippi River Lock and Dam 11
The primary purpose of Mississippi River Lock and Dam 11 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 Mississippi River near Dubuque.
The dam stands 43 feet tall and stretches 5,130 feet across, creates a reservoir covering 19,613 acres, has a maximum storage capacity of 170,000 acre-feet, and collects water from a drainage area of 81,600 square miles. Completed in 1937, 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 06/04/2024.
At 43 feet, this dam is taller than 89% of dams nationwide.
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Location
| State | Iowa |
| County | Dubuque |
| Nearest City | Dubuque |
| River/Stream | Mississippi River |
| Coordinates | 42.54014, -90.64463 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 43 ft |
| Dam Length | 5,130 ft |
| Year Completed | 1937 (89 years old) |
Storage & Hydraulics
| NID Storage | 170,000 acre-ft |
| Max Storage | 170,000 acre-ft |
| Surface Area | 19,613 acres |
| Drainage Area | 81,600 sq mi |
| Max Discharge | 326,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - Rock Island District |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 06/04/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IA00003 |
| Federal ID | IA00003 |
| More Info | State Dam Safety Program |