Alpine Dam
Alpine Dam is an earth dam located in Winnebago County, Illinois, built in 1942. It carries a High hazard potential classification.
About Alpine Dam
The primary purpose of Alpine 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 City Of Rockford (local government). It impounds the Keith Creek near Rockford.
The dam stands 48 feet tall and stretches 600 feet across, has a maximum storage capacity of 1,770 acre-feet, and collects water from a drainage area of 7 square miles. Completed in 1942, 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 10/16/2025.
At 48 feet, this dam is taller than 92% 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 | Winnebago |
| Nearest City | Rockford |
| River/Stream | Keith Creek |
| Coordinates | 42.27146, -89.02578 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 48 ft |
| Dam Height | 48 ft |
| Dam Length | 600 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 1,770 acre-ft |
| Max Storage | 1,770 acre-ft |
| Drainage Area | 7 sq mi |
| Max Discharge | 17,429 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | CITY OF ROCKFORD |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 10/16/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00109 |
| Federal ID | IL00109 |
| More Info | State Dam Safety Program |