Gateway Medical Lake Dam is an earth dam located in Madison County, Illinois, built in 1939. It carries a High hazard potential classification.
Dam profile
NID height · 31 ft31 ft tall and 230 ft long, taller than 72% 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 embankment section and the water level is illustrative.
About Gateway Medical Lake Dam
The primary purpose of Gateway Medical Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Granite City Hospital Co., LLC (private). It impounds the Trib Cahokia Creek near Edwardsville.
The dam stands 31 feet tall and stretches 230 feet across, has a maximum storage capacity of 26 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1939, the structure is well-established, with more than 75 years of service.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 07/11/2025.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Illinois dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Illinois |
| County | Madison |
| Nearest City | Edwardsville |
| River/Stream | Trib Cahokia Creek |
| Coordinates | 38.79869, -89.97288 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 31 ft |
| Dam Height | 31 ft |
| Dam Length | 230 ft |
| Year Completed | 1939 (87 years old) |
Storage & Hydraulics
| NID Storage | 26 acre-ft |
| Max Storage | 26 acre-ft |
| Normal Storage | 16 acre-ft |
| Drainage Area | 0 sq mi |
| Max Discharge | 468 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Granite City Hospital Co., LLC |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 07/11/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50619 |
| Federal ID | IL50619 |
| More Info | State Dam Safety Program |