Tomhannock Reservoir Dam
Tomhannock Reservoir Dam is a concrete dam located in Rensselaer County, New York, built in 1905. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Tomhannock Reservoir Dam
The primary purpose of Tomhannock Reservoir 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 City Of Troy (local government). It impounds the Tomhannock Creek near Pittstown & Schaghticoke.
The dam stands 68 feet tall and stretches 700 feet across, creates a reservoir covering 1,742 acres, has a maximum storage capacity of 56,600 acre-feet, and collects water from a drainage area of 66 square miles. Completed in 1905, 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 01/09/2025.
At 68 feet, this dam is taller than 96% 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 | Rensselaer |
| Nearest City | Pittstown & Schaghticoke |
| River/Stream | Tomhannock Creek |
| Coordinates | 42.87056, -73.58333 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 68 ft |
| Dam Height | 68 ft |
| Dam Length | 700 ft |
| Year Completed | 1905 (121 years old) |
Storage & Hydraulics
| NID Storage | 56,600 acre-ft |
| Max Storage | 56,600 acre-ft |
| Normal Storage | 39,521 acre-ft |
| Surface Area | 1,742 acres |
| Drainage Area | 66 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | CITY OF TROY |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 01/09/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY00117 |
| Federal ID | NY00117 |
| More Info | State Dam Safety Program |