Pierce Lake Dam
Pierce Lake Dam is an earth dam located in Winnebago County, Illinois, built in 1960. It carries a High hazard potential classification.
About Pierce Lake Dam
The primary purpose of Pierce Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Illinois Department Of Natural Resources (state). It impounds the Willow Creek near North Fork.
The dam stands 46 feet tall and stretches 470 feet across, creates a reservoir covering 162 acres, has a maximum storage capacity of 4,785 acre-feet, and collects water from a drainage area of 13 square miles. Completed in 1960, the structure is well into its service life at over 50 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 07/23/2025.
At 46 feet, this dam is taller than 91% 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 | North Fork |
| River/Stream | Willow Creek |
| Coordinates | 42.34622, -88.98694 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 46 ft |
| Dam Height | 46 ft |
| Dam Length | 470 ft |
| Year Completed | 1960 (66 years old) |
Storage & Hydraulics
| NID Storage | 4,785 acre-ft |
| Max Storage | 4,785 acre-ft |
| Normal Storage | 2,660 acre-ft |
| Surface Area | 162 acres |
| Drainage Area | 13 sq mi |
| Max Discharge | 30,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | ILLINOIS DEPARTMENT OF NATURAL RESOURCES |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 07/23/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL01011 |
| Federal ID | IL01011 |
| More Info | State Dam Safety Program |