Melvin Price Locks and Dam is a concrete dam located in St. Charles County, Illinois, built in 1990. It carries a Significant hazard potential classification.
Dam profile
NID height · 77 ft77 ft tall and 1,700 ft long, taller than 97% of U.S. dams with a recorded height. Height is drawn to scale against a ten-story building, about 100 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Melvin Price Locks and Dam
The primary purpose of Melvin Price Locks 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 - St. Louis District (federal). It impounds the Mississippi River near Alton.
The dam stands 77 feet tall and stretches 1,700 feet across, creates a reservoir covering 30,000 acres, has a maximum storage capacity of 238,000 acre-feet, and collects water from a drainage area of 171,470 square miles. Completed in 1990, the structure is 36 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. An emergency action plan is in place for this dam. The most recent inspection on record was 04/02/2024.
At 77 feet, this dam is taller than 97% of all dams in the United States.
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Location
| State | Illinois |
| County | St. Charles |
| Nearest City | Alton |
| River/Stream | Mississippi River |
| Coordinates | 38.86691, -90.15488 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 77 ft |
| Dam Height | 72 ft |
| Dam Length | 1,700 ft |
| Year Completed | 1990 (36 years old) |
Storage & Hydraulics
| NID Storage | 238,000 acre-ft |
| Max Storage | 238,000 acre-ft |
| Normal Storage | 238,000 acre-ft |
| Surface Area | 30,000 acres |
| Drainage Area | 171,470 sq mi |
| Max Discharge | 650,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Navigation |
| Owner | USACE - St. Louis District |
| Owner Type | Federal |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 04/02/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50077 |
| Federal ID | IL50077 |
| More Info | State Dam Safety Program |