High Hill Farms Dam
High Hill Farms Dam is an earth dam located in McHenry County, Illinois, built in 1977. It carries a High hazard potential classification.
About High Hill Farms Dam
The primary purpose of High Hill Farms 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 Algonquin (local government). It impounds the Rat Creek near Algonquin.
The dam stands 23 feet tall and stretches 575 feet across, and has a maximum storage capacity of 76 acre-feet. Completed in 1977, the structure is 49 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 06/12/2025.
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 | McHenry |
| Nearest City | Algonquin |
| River/Stream | Rat Creek |
| Coordinates | 42.16531, -88.30656 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 575 ft |
| Year Completed | 1977 (49 years old) |
Storage & Hydraulics
| NID Storage | 76 acre-ft |
| Max Storage | 76 acre-ft |
| Normal Storage | 2 acre-ft |
| Max Discharge | 600 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | VILLAGE OF ALGONQUIN |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 06/12/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL50356 |
| Federal ID | IL50356 |
| More Info | State Dam Safety Program |