Iroquois

St. Lawrence River· St. Lawrence, New York· Built 1958· Concrete· 67 ft tall
Significant Hazard Hydroelectric Navigation State Government

Key Takeaway

Iroquois is classified as significant hazard in New York. It was completed in 1958 and is 68 years old. Its primary use is hydroelectric. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 67 ft (taller than 95.9% in NY)
Dam Length1,980 ft
Dam TypeConcrete
Max Storage803.0K acre-ft
Normal Storage750.0K acre-ft
Surface Area37,500 acres
Drainage Area300,000 sq mi
Max Discharge385,000 cfs
Year Completed1958 (68 years old)
NID IDNY00676

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: Yes
Last Inspection: August 4, 2022
State Regulated: No

Ownership

New York Power Authority

State Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Iroquois?

Iroquois 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 Iroquois?

Iroquois is owned by New York Power Authority (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Iroquois built?

Iroquois was completed in 1958, making it 68 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 Iroquois?

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

How tall is Iroquois?

Iroquois has a dam height of 67 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 Iroquois last inspected?

Iroquois was last inspected on August 4, 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.