Mississippi River Lock and Dam 22 is a concrete dam located in Ralls County, Missouri, built in 1938. It carries a Significant hazard potential classification.
Dam profile
NID height · 32 ft32 ft tall and 3,264 ft long, taller than 74% 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 22
The primary purpose of Mississippi River Lock and Dam 22 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 Ashburn.
The dam stands 32 feet tall and stretches 3,264 feet across, creates a reservoir covering 8,540 acres, has a maximum storage capacity of 80,000 acre-feet, and collects water from a drainage area of 137,500 square miles. Completed in 1938, 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 08/10/2023.
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Location
| State | Missouri |
| County | Ralls |
| Nearest City | Ashburn |
| River/Stream | Mississippi River |
| Coordinates | 39.63670, -91.24817 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 32 ft |
| Dam Length | 3,264 ft |
| Year Completed | 1938 (88 years old) |
Storage & Hydraulics
| NID Storage | 80,000 acre-ft |
| Max Storage | 80,000 acre-ft |
| Surface Area | 8,540 acres |
| Drainage Area | 137,500 sq mi |
| Max Discharge | 537,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - Rock Island District |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 08/10/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MO10305 |
| Federal ID | MO10305 |
| More Info | State Dam Safety Program |