Gregg Lake Dam

GREAT BROOK· Hillsborough, New Hampshire· Built 1908· Concrete· 12 ft tall

High Hazard Recreation Local Government

Key Takeaway

Gregg Lake Dam is classified as high hazard in New Hampshire. It was completed in 1908 and is 118 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	12 ft (taller than 28.2% in NH)
Dam Length	210 ft
Dam Type	Concrete
Max Storage	1.4K acre-ft
Normal Storage	1.0K acre-ft

Surface Area	201 acres
Drainage Area	4 sq mi
Max Discharge	1,566 cfs
Year Completed	1908 (118 years old)
Year Modified	1982
NID ID	NH00056

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: September 1, 2021

State Regulated: Yes

Regulatory Agency: NH DES

Ownership

TOWN OF ANTRIM

Local Government

Nearby Dams

Steels Pond

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Evas Marsh Dam

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Low Hazard 9 ft

Willard Pond Dam

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Low Hazard 8 ft

Antrim Sewage Lagoons Dam

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Moose Brook Dam

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Monadnock Paper Indust Lag Dam

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Significant Hazard 14 ft

Wildlife Pond Dam

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Unknown 10 ft

Paper Mill

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Frequently Asked Questions

What is the hazard classification of Gregg Lake Dam?

Gregg Lake 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 Gregg Lake Dam?

Gregg Lake Dam is owned by TOWN OF ANTRIM (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Gregg Lake Dam built?

Gregg Lake Dam was completed in 1908, making it 118 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 Gregg Lake Dam?

Gregg Lake 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 Gregg Lake Dam?

Gregg Lake Dam has a dam height of 12 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 Gregg Lake Dam last inspected?

Gregg Lake Dam was last inspected on September 1, 2021. 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.