Ilion Reservoir #3 Dam
Ilion Reservoir #3 Dam is an earth dam located in Herkimer County, New York, built in 1921. It carries a High hazard potential classification and has a poor condition assessment.
About Ilion Reservoir #3 Dam
The primary purpose of Ilion Reservoir #3 Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Village Of Ilion (local government). It impounds the Tr-mohawk River near Ilion.
The dam stands 76 feet tall and stretches 975 feet across, creates a reservoir covering 41 acres, has a maximum storage capacity of 737 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1921, the structure is over a century 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. Its condition is rated poor, meaning the dam has recognized safety deficiencies that require remediation to address risks. An emergency action plan is in place for this dam. The most recent inspection on record was 01/30/2024.
At 76 feet, this dam is taller than 97% of all dams in the United States.
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 New York 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 | New York |
| County | Herkimer |
| Nearest City | Ilion |
| River/Stream | Tr-mohawk River |
| Coordinates | 42.98694, -75.03250 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 76 ft |
| Dam Height | 76 ft |
| Dam Length | 975 ft |
| Year Completed | 1921 (105 years old) |
Storage & Hydraulics
| NID Storage | 737 acre-ft |
| Max Storage | 737 acre-ft |
| Normal Storage | 491 acre-ft |
| Surface Area | 41 acres |
| Drainage Area | 1 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | VILLAGE OF ILION |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Poor |
| Last Inspection | 01/30/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY00184 |
| Federal ID | NY00184 |
| More Info | State Dam Safety Program |