Long Sault
Long Sault is a concrete dam located in St. Lawrence County, New York, built in 1958. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Long Sault
The primary purpose of Long Sault is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by New York Power Authority (state). It impounds the St. Lawrence River near Cornwall.
The dam stands 132 feet tall and stretches 2,960 feet across, creates a reservoir covering 37,500 acres, has a maximum storage capacity of 803,000 acre-feet, and collects water from a drainage area of 300,000 square miles. Completed in 1958, 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. 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 08/03/2022.
At 132 feet, this dam is taller than 99% 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 | St. Lawrence |
| Nearest City | Cornwall |
| River/Stream | St. Lawrence River |
| Coordinates | 44.99640, -74.86460 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 132 ft |
| Dam Height | 104 ft |
| Dam Length | 2,960 ft |
| Year Completed | 1958 (68 years old) |
Storage & Hydraulics
| NID Storage | 803,000 acre-ft |
| Max Storage | 803,000 acre-ft |
| Normal Storage | 750,000 acre-ft |
| Surface Area | 37,500 acres |
| Drainage Area | 300,000 sq mi |
| Max Discharge | 1,250,000 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | New York Power Authority |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/03/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | NY00677 |
| Federal ID | NY00678S001 |
| More Info | State Dam Safety Program |