Stratton Lock and Dam is a gravity dam located in McHenry County, Illinois, built in 1939. It carries a Significant hazard potential classification.
Dam profile
NID height · 7 ft7 ft tall and 275 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Stratton Lock and Dam
The primary purpose of Stratton Lock and 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 Illinois Department of Natural Resources (state). It impounds the Fox River near Holiday Hills.
The dam stands 7 feet tall and stretches 275 feet across, creates a reservoir covering 8,700 acres, has a maximum storage capacity of 113,000 acre-feet, and collects water from a drainage area of 1,243 square miles. Completed in 1939, the structure is well-established, with more than 75 years of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. An emergency action plan is in place for this dam. The most recent inspection on record was 10/03/2025.
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Location
| State | Illinois |
| County | McHenry |
| Nearest City | Holiday Hills |
| River/Stream | Fox River |
| Coordinates | 42.30917, -88.25139 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 7 ft |
| Dam Height | 7 ft |
| Dam Length | 275 ft |
| Year Completed | 1939 (87 years old) |
Storage & Hydraulics
| NID Storage | 113,000 acre-ft |
| Max Storage | 113,000 acre-ft |
| Normal Storage | 37,000 acre-ft |
| Surface Area | 8,700 acres |
| Drainage Area | 1,243 sq mi |
| Max Discharge | 12,759 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Illinois Department of Natural Resources |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Last Inspection | 10/03/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00288 |
| Federal ID | IL00288 |
| More Info | State Dam Safety Program |