Coffeen Gmf Gypsum Stack Dam
High HazardNot Available ConditionEmergency Action Plan: Yes
Location
| State | Illinois |
| County | Montgomery |
| Nearest City | COFFEEN |
| River/Stream | MCDAVID BRANCH EAST FORK SHOAL |
| Coordinates | 39.07141, -89.39868 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 108 ft |
| Dam Height | 108 ft |
| Dam Length | 5,100 ft |
Storage & Hydraulics
| NID Storage | 2,355 acre-ft |
| Max Storage | 2,355 acre-ft |
| Surface Area | 38 acres |
| Drainage Area | 38 sq mi |
| Max Discharge | 1,100 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Debris Control |
| Owner | DYNEGY MIDWEST GENERATION, INC. |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 09/17/2025 |
| Emergency Action Plan | Yes |