Lower Trio Pond Dam

POND BROOK· Coos, New Hampshire· Built 1936· Earth· 11 ft tall
Low Hazard Recreation State Government

Key Takeaway

Lower Trio Pond Dam is classified as low hazard in New Hampshire. It was completed in 1936 and is 90 years old. Its primary use is recreation.

Physical Details

Dam Height 11 ft (taller than 23.8% in NH)
Dam Length120 ft
Dam TypeEarth
Max Storage355 acre-ft
Normal Storage182 acre-ft
Surface Area69 acres
Drainage Area2 sq mi
Max Discharge367 cfs
Year Completed1936 (90 years old)
Year Modified1981
NID IDNH00373

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

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

Emergency Action Plan: No
Last Inspection: June 15, 2022
State Regulated: Yes
Regulatory Agency: NH DES

Ownership

NH FISH AND GAME DEPARTMENT

State Government

Nearby Dams

Little Bog Pond Dam

Coos, NH

Low Hazard 18 ft

Phillips Pond Dam

Coos, NH

Low Hazard 15 ft

Stratford Bog Pond Dam

Coos, NH

High Hazard 16 ft

Pontook

Coos, NH

Low Hazard 15 ft

Brooklyn

Coos, NH

Significant Hazard 19 ft

Weston

Coos, NH

Low Hazard 20 ft

Groveton Municipal Lagoons Dam

Coos, NH

Significant Hazard 20 ft

Groveton Paper Mill Lagoons Dam

Coos, NH

Significant Hazard 25 ft

Frequently Asked Questions

What is the hazard classification of Lower Trio Pond Dam?

Lower Trio Pond Dam is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Lower Trio Pond Dam?

Lower Trio Pond Dam is owned by NH FISH AND GAME DEPARTMENT (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Lower Trio Pond Dam built?

Lower Trio Pond Dam was completed in 1936, making it 90 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 Lower Trio Pond Dam?

Lower Trio Pond 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 Lower Trio Pond Dam?

Lower Trio Pond Dam has a dam height of 11 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 Lower Trio Pond Dam last inspected?

Lower Trio Pond Dam was last inspected on June 15, 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.