Ayer Reservoir Dam Reservoir Report

Last Updated: December 15, 2025

Ayer Reservoir Dam, located in San Juan, Washington, was completed in 1964 and serves as a private recreational spot for water resource and climate enthusiasts.


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Summary

The dam is primarily made of earth and stone, with a hydraulic height of 32 feet and a structural height of 30 feet. It holds a maximum storage capacity of 135 acre-feet and covers a surface area of 10.3 acres, drawing water from the Tr-East Sound river or stream.

Managed by the Washington Dept of Ecology, Ayer Reservoir Dam has a low hazard potential and is not currently rated for condition assessment. While the dam has not undergone recent inspections, it is state-regulated, permitted, and inspected, ensuring safety and compliance with regulatory standards. The dam's emergency action plan status and risk management measures are currently unreported, leaving room for improvement in disaster preparedness and risk mitigation.

Despite its modest size and capacity, Ayer Reservoir Dam offers a unique recreational experience for visitors in the area. With its scenic location and tranquil waters, the dam provides a peaceful retreat for nature enthusiasts and outdoor adventurers alike. As interest in water resources and climate conservation grows, Ayer Reservoir Dam stands as a testament to the importance of sustainable management and preservation of our natural resources.

Year Completed

1964

River Or Stream

Tr-East Sound

Primary Dam Type

Earth

Surface Area

10.3

Hydraulic Height

32

Drainage Area

0.5

Nid Storage

135

Structural Height

30

Hazard Potential

Low

Foundations

Soil

Nid Height

32
       
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.