Hollow Dam
Hollow Dam is a concrete dam located in St. Lawrence County, New York, built in 1987. It carries a Low hazard potential classification and has a satisfactory condition assessment.
About Hollow Dam
The primary purpose of Hollow Dam 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 Ampersand Hollow Dam Hydro, Llc (private). It impounds the West Branch Oswegatchie River near Talcville.
The dam stands 31 feet tall and stretches 385 feet across, creates a reservoir covering 16 acres, has a maximum storage capacity of 220 acre-feet, and collects water from a drainage area of 294 square miles. Completed in 1987, the structure is 39 years old.
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. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 08/12/2025.
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Location
| State | New York |
| County | St. Lawrence |
| Nearest City | Talcville |
| River/Stream | West Branch Oswegatchie River |
| Coordinates | 44.29710, -75.33630 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 31 ft |
| Dam Height | 31 ft |
| Dam Length | 385.5 ft |
| Year Completed | 1987 (39 years old) |
Storage & Hydraulics
| NID Storage | 220 acre-ft |
| Max Storage | 220 acre-ft |
| Normal Storage | 220 acre-ft |
| Surface Area | 16 acres |
| Drainage Area | 294 sq mi |
| Max Discharge | 10,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Ampersand Hollow Dam Hydro, LLC |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Satisfactory |
| Last Inspection | 08/12/2025 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NY01604 |
| Federal ID | NY01604 |
| More Info | State Dam Safety Program |