Mongaup

Mongaup River· Sullivan, New York· Built 1925· Gravity· 45 ft tall

High Hazard Hydroelectric Private

Key Takeaway

Mongaup is classified as high hazard in New York. It was completed in 1925 and is 101 years old. Its primary use is hydroelectric. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height	45 ft (taller than 90.4% in NY)
Dam Length	384 ft
Dam Type	Gravity
Max Storage	1.8K acre-ft
Normal Storage	1.8K acre-ft

Surface Area	120 acres
Drainage Area	158 sq mi
Max Discharge	34,000 cfs
Year Completed	1925 (101 years old)
NID ID	NY00321

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

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

Emergency Action Plan: Yes

Last Inspection: August 12, 2022

State Regulated: No

Ownership

Eagle Creek Hydro Power, LLC

Private

Nearby Dams

Lower Lake Metaugue Dam

Sullivan, NY

Low Hazard 10 ft

Burnt Hope Dam

Sullivan, NY

Low Hazard 19 ft

Swinging Bridge

Sullivan, NY

High Hazard 135 ft

Lebanon Lake Dam

Sullivan, NY

Low Hazard 20 ft

Ruddick Pond Dam

Sullivan, NY

Low Hazard 8 ft

Cliff Lake

Sullivan, NY

High Hazard 36 ft

Hartwood Club Dam

Sullivan, NY

Low Hazard 8 ft

Merriewold Lake Dam

Sullivan, NY

Significant Hazard 10 ft

Frequently Asked Questions

What is the hazard classification of Mongaup?

Mongaup is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Mongaup?

Mongaup is owned by Eagle Creek Hydro Power, LLC (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mongaup built?

Mongaup was completed in 1925, making it 101 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 Mongaup?

Mongaup 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 Mongaup?

Mongaup has a dam height of 45 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 Mongaup last inspected?

Mongaup was last inspected on August 12, 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.