Dynegy/havana Station/cell 1, Polishing P
Dynegy/havana Station/cell 1, Polishing P is an earth dam located in Mason County, Illinois, built in 1993. It carries a High hazard potential classification.
About Dynegy/havana Station/cell 1, Polishing P
The primary purpose of Dynegy/havana Station/cell 1, Polishing P 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, Inc. (public utility). It impounds the Trib Illinois River near Havana.
The dam stands 26 feet tall and stretches 9,200 feet across, and has a maximum storage capacity of 606 acre-feet. Completed in 1993, the structure is 33 years old.
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.
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 | 40.27886, -90.07561 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 26 ft |
| Dam Height | 26 ft |
| Dam Length | 9,200 ft |
| Year Completed | 1993 (33 years old) |
Storage & Hydraulics
| NID Storage | 606 acre-ft |
| Max Storage | 606 acre-ft |
| Normal Storage | 482 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Debris Control |
| Owner | DYNEGY MIDWEST GENERATION, INC. |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 10/07/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50185 |
| Federal ID | IL50185 |
| More Info | State Dam Safety Program |