Thorne Dam

WASSAIC CREEK· Dutchess, New York· Built 1905· Masonry· 38 ft tall

High Hazard Recreation Private

Key Takeaway

Thorne Dam is classified as high hazard in New York. It was completed in 1905 and is 121 years old. Its primary use is recreation. 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	38 ft (taller than 87.2% in NY)
Dam Length	227 ft
Dam Type	Masonry
Max Storage	44 acre-ft
Normal Storage	35 acre-ft

Surface Area	4 acres
Drainage Area	21 sq mi
Max Discharge	1,790 cfs
Year Completed	1905 (121 years old)
NID ID	NY00793

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: April 16, 2019

State Regulated: Yes

Regulatory Agency: NYS DEC

Ownership

THORNE'S DAM LLC

Private

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Hanes & Bontecou Marsh Dam

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Tamarack Swamp Dam

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Chauncey Stillman Dam

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Crane Pond Dam

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Dieterich Dam #2

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Round Pond Dam

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Low Hazard 10 ft

Hilltop Pond Dam

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Significant Hazard 11 ft

Arbor Pond Dam

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Low Hazard 27 ft

Frequently Asked Questions

What is the hazard classification of Thorne Dam?

Thorne Dam 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 Thorne Dam?

Thorne Dam is owned by THORNE'S DAM LLC (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Thorne Dam built?

Thorne Dam 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 Thorne Dam?

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

How tall is Thorne Dam?

Thorne Dam has a dam height of 38 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 Thorne Dam last inspected?

Thorne Dam was last inspected on April 16, 2019. 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.