Ayers Pond Dam Reservoir Report

Last Updated: December 16, 2025

Ayers Pond Dam, located in Barrington, New Hampshire, is a state-regulated structure owned by the state with a primary purpose of recreation.


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Summary

Built in 1810, this Earth type dam stands at a height of 18 feet and has a length of 375 feet, providing a storage capacity of 1767 acre-feet with a surface area of 236 acres. The dam controls the flow of the Isinglass River and has an uncontrolled spillway with a width of 6 feet.

The dam's inspection frequency is every four years, with the last assessment in November 2017 revealing a fair condition and significant hazard potential. Despite its age, Ayers Pond Dam has been maintained to meet state regulations, with the NHDES DAM BUREAU overseeing its permitting, inspection, and enforcement. With a moderate risk assessment rating, the dam's risk management measures and emergency action plan are in place to ensure public safety in case of any unforeseen events.

As a focal point for recreational activities in the area, Ayers Pond Dam continues to serve as a vital resource for water enthusiasts and climate advocates. Its historical significance, combined with its role in regulating water flow and providing a recreational outlet, makes it an essential element in the local ecosystem and a valuable asset for the community.

Year Completed

1810

Dam Length

375

Dam Height

18

River Or Stream

TR ISINGLASS RIVER

Primary Dam Type

Earth

Surface Area

236

Drainage Area

2.35

Nid Storage

1767

Hazard Potential

Significant

Foundations

Unlisted/Unknown

Nid Height

18
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.