Dynegy/havana Sta/east Ash Pond Dam is an earth dam located in Mason County, Illinois. It carries a High hazard potential classification.
Dam profile
NID height · 36 ft36 ft tall and 7,574 ft long, taller than 82% 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 Dynegy/havana Sta/east Ash Pond Dam
The primary purpose of Dynegy/havana Sta/east Ash Pond Dam is debris control. The dam is designed to catch sediment, rocks, and debris carried by flowing water — particularly important in areas prone to mudslides or heavy erosion. The dam is owned by Dynegy Midwest Generation, LLC (public utility). It impounds the Trib Illinois River near Havana.
The dam stands 36 feet tall and stretches 7,574 feet across, creates a reservoir covering 43 acres, has a maximum storage capacity of 1,440 acre-feet, and collects water from a drainage area of 0 square miles.
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 10/07/2025.
At 36 feet, this dam is taller than 82% of dams nationwide.
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 | Mason |
| Nearest City | Havana |
| River/Stream | Trib Illinois River |
| Coordinates | 40.28497, -90.06835 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 36 ft |
| Dam Height | 36 ft |
| Dam Length | 7,574 ft |
Storage & Hydraulics
| NID Storage | 1,440 acre-ft |
| Max Storage | 1,440 acre-ft |
| Normal Storage | 613 acre-ft |
| Surface Area | 43 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 244 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Debris Control |
| Owner | Dynegy Midwest Generation, LLC |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 10/07/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50483 |
| Federal ID | IL50483 |
| More Info | State Dam Safety Program |