Grasslands Basin Dam
Grasslands Basin Dam is an earth dam located in Cook County, Illinois. It carries a High hazard potential classification.
About Grasslands Basin Dam
The primary purpose of Grasslands Basin Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Village Of Orland Park (local government). It impounds the Trib Marley Creek.
The dam stands 10 feet tall, has a maximum storage capacity of 22 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 10/29/2025.
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 | Cook |
| River/Stream | Trib Marley Creek |
| Coordinates | 41.58517, -87.89807 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 10 ft |
| Dam Height | 10 ft |
Storage & Hydraulics
| NID Storage | 22 acre-ft |
| Max Storage | 22 acre-ft |
| Drainage Area | 0 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | VILLAGE OF ORLAND PARK |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 10/29/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL55173 |
| Federal ID | IL55173 |
| More Info | State Dam Safety Program |