Pleasant Lake Dam

TR BLACKWATER RIVER· Merrimack, New Hampshire· Built 1850· Earth· 13 ft tall
High Hazard Recreation Local Government

Key Takeaway

Pleasant Lake Dam is classified as high hazard in New Hampshire. It was completed in 1850 and is 176 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 13 ft (taller than 36.5% in NH)
Dam Length360 ft
Dam TypeEarth
Max Storage9.3K acre-ft
Normal Storage6.8K acre-ft
Surface Area604 acres
Drainage Area11 sq mi
Max Discharge1,689 cfs
Year Completed1850 (176 years old)
Year Modified2017
NID IDNH00362

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: July 7, 2021
State Regulated: Yes
Regulatory Agency: NH DES

Ownership

TOWN OF NEW LONDON

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Pleasant Lake Dam?

Pleasant 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 Pleasant Lake Dam?

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

When was Pleasant Lake Dam built?

Pleasant Lake Dam was completed in 1850, making it 176 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 Pleasant Lake Dam?

Pleasant 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 Pleasant Lake Dam?

Pleasant Lake Dam has a dam height of 13 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 Pleasant Lake Dam last inspected?

Pleasant Lake Dam was last inspected on July 7, 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.