Lake Joy Dam is an earth dam located in Clinton County, Illinois, built in 1946. It carries a Low hazard potential classification.
Dam profile
NID height · 23 ft23 ft tall and 292 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Lake Joy Dam
The primary purpose of Lake Joy Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Okaw Valley Boy Scouts (private). It impounds the Trib Little York Branch near Posey-offstream.
The dam stands 23 feet tall and stretches 292 feet across, and has a maximum storage capacity of 87 acre-feet. Completed in 1946, the structure is well-established, with more than 75 years of service.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. The most recent inspection on record was 07/16/2025.
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Location
| State | Illinois |
| County | Clinton |
| Nearest City | Posey-offstream |
| River/Stream | Trib Little York Branch |
| Coordinates | 38.57541, -89.39501 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 292 ft |
| Year Completed | 1946 (80 years old) |
Storage & Hydraulics
| NID Storage | 87 acre-ft |
| Max Storage | 87 acre-ft |
| Normal Storage | 62 acre-ft |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Okaw Valley Boy Scouts |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 07/16/2025 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IL00854 |
| Federal ID | IL00854 |
| More Info | State Dam Safety Program |