Harrisville

West Branch Oswegatchie River· Lewis, New York· Built 1905· Concrete· 25 ft tall
Low Hazard Hydroelectric Private

Key Takeaway

Harrisville is classified as low hazard in New York. It was completed in 1905 and is 121 years old. Its primary use is hydroelectric.

Physical Details

Dam Height 25 ft (taller than 69.7% in NY)
Dam Length385 ft
Dam TypeConcrete
Max Storage84 acre-ft
Normal Storage84 acre-ft
Surface Area25 acres
Drainage Area198 sq mi
Max Discharge8,500 cfs
Year Completed1905 (121 years old)
NID IDNY00679

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

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

Emergency Action Plan: No
Last Inspection: July 26, 2018
State Regulated: Yes
Regulatory Agency: NYS DEC

Ownership

EONY Generation Limited

Private

Nearby Dams

Alpina Dam

Lewis, NY

Low Hazard 7 ft

Hollow Dam

St. Lawrence, NY

Significant Hazard 31 ft

Blanchard Pond Dam

Lewis, NY

Low Hazard 13 ft

Emeryville

St. Lawrence, NY

Low Hazard 25 ft

Niagara Mohawk Power Dam

St. Lawrence, NY

Significant Hazard 11 ft

South Edwards

St. Lawrence, NY

Significant Hazard 48 ft

Frequently Asked Questions

What is the hazard classification of Harrisville?

Harrisville is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Harrisville?

Harrisville is owned by EONY Generation Limited (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Harrisville built?

Harrisville was completed in 1905, making it 121 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 Harrisville?

Harrisville 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 Harrisville?

Harrisville has a dam height of 25 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 Harrisville last inspected?

Harrisville was last inspected on July 26, 2018. 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.