Williams Reservoir Report

Last Updated: December 15, 2025

Williams is a concrete dam located in Londonderry, Vermont, along the West River.


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Summary

Built in 1900, this structure stands at a height of 20 feet and has a length of 117 feet, with a storage capacity of 75 acre-feet. Despite its age, Williams is regulated and inspected by the Vermont Department of Environmental Conservation, ensuring its safety and compliance with state regulations. The dam has a low hazard potential, but its condition has been assessed as poor, indicating a need for maintenance and potential upgrades to ensure its long-term functionality.

The primary purpose of Williams is classified as "Other," and it serves various functions beyond just water storage. The dam is owned by the local government and falls under state jurisdiction for regulation, permitting, inspection, and enforcement. The surrounding area has a drainage area of 44 square miles, with a surface area of 8 acres. Although the dam has not undergone recent modifications, its last inspection in August 2015 highlighted the need for improvements to meet safety standards and ensure its resilience in the face of potential climate challenges.

In the event of an emergency, the dam's Emergency Action Plan (EAP) status is unknown, raising potential concerns about preparedness and response capabilities. With a designated inspection frequency of 10 years, stakeholders may need to prioritize addressing the poor condition assessment to mitigate risks and ensure the continued functionality of Williams for water resource management and climate resilience in the region.

Year Completed

1900

Dam Length

117

Dam Height

20

River Or Stream

WEST RIVER

Primary Dam Type

Concrete

Surface Area

8

Hydraulic Height

20

Drainage Area

44

Nid Storage

75

Structural Height

20

Hazard Potential

Low

Foundations

Rock

Nid Height

20
       
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.