Hollow Dam

West Branch Oswegatchie River· St. Lawrence, New York· Built 1987· Concrete· 31 ft tall
Significant Hazard Hydroelectric Private

Key Takeaway

Hollow Dam is classified as significant hazard in New York. It was completed in 1987 and is 39 years old. Its primary use is hydroelectric. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 31 ft (taller than 80.7% in NY)
Dam Length386 ft
Dam TypeConcrete
Max Storage220 acre-ft
Normal Storage220 acre-ft
Surface Area16 acres
Drainage Area294 sq mi
Max Discharge10,000 cfs
Year Completed1987 (39 years old)
NID IDNY01604

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
Last Inspection: September 23, 2022
State Regulated: No

Ownership

Ampersand Hollow Dam Hydro, LLC

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Hollow Dam?

Hollow Dam is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Hollow Dam?

Hollow Dam is owned by Ampersand Hollow Dam Hydro, LLC (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Hollow Dam built?

Hollow Dam was completed in 1987, making it 39 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Hollow Dam?

Hollow Dam serves the following purposes: Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Hollow Dam?

Hollow Dam has a dam height of 31 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Hollow Dam last inspected?

Hollow Dam was last inspected on September 23, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.