Jerry F. Costello Lock and Dam is a concrete dam located in Randolph County, Illinois, built in 1974. It carries a Significant hazard potential classification.
Dam profile
NID height · 81 ft81 ft tall and 603 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 Jerry F. Costello Lock and Dam
The primary purpose of Jerry F. Costello 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 - St. Louis District (federal). It impounds the Kaskaskia River near Modoc.
The dam stands 81 feet tall and stretches 603 feet across, creates a reservoir covering 2,618 acres, has a maximum storage capacity of 25,246 acre-feet, and collects water from a drainage area of 5,790 square miles. Completed in 1974, 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. An emergency action plan is in place for this dam. The most recent inspection on record was 03/29/2023.
At 81 feet, this dam is taller than 97% of all dams in the United States.
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Location
| State | Illinois |
| County | Randolph |
| Nearest City | Modoc |
| River/Stream | Kaskaskia River |
| Coordinates | 37.98419, -89.94597 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 81 ft |
| Dam Height | 66 ft |
| Dam Length | 603 ft |
| Year Completed | 1974 (52 years old) |
Storage & Hydraulics
| NID Storage | 25,246 acre-ft |
| Max Storage | 25,246 acre-ft |
| Normal Storage | 22,183 acre-ft |
| Surface Area | 2,618 acres |
| Drainage Area | 5,790 sq mi |
| Max Discharge | 62,000 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 | 03/29/2023 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00115 |
| Federal ID | IL00115 |
| More Info | State Dam Safety Program |