Timberlakes Dam Reservoir Report

Last Updated: December 14, 2025

Located in Mason, Washington, Timberlakes Dam stands as a private recreational structure along Tr-Campbell Creek.


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Summary

Built in 1968, this earth dam serves as a popular spot for outdoor enthusiasts seeking activities like fishing, boating, and hiking in the surrounding area. With a maximum storage capacity of 904 acre-feet and a normal storage level of 828 acre-feet, the dam covers a surface area of 15.2 acres and has a drainage area of 2.15 square miles.

Standing at a hydraulic height of 29 feet and a structural height of 27 feet, Timberlakes Dam has a length of 205 feet and a maximum discharge capacity of 404 cfs. Despite its high hazard potential, the dam is currently deemed to be in satisfactory condition as of the last assessment in May 2018. The dam is regulated by the Washington Department of Ecology, with inspections conducted every 5 years to ensure its safety and compliance with state regulations. In case of emergencies, an Emergency Action Plan (EAP) is in place, although details on its preparation and guidelines adherence are not specified in the data provided.

Representing a vital water resource and climate asset in the region, Timberlakes Dam serves as a key recreational hub with its serene surroundings and abundant water-based activities. Managed by private owners, the dam contributes to the local ecosystem while offering a safe and enjoyable environment for residents and visitors alike. With its crucial role in providing water storage and outdoor recreation opportunities, Timberlakes Dam embodies the harmonious blend of human infrastructure and natural beauty in the Pacific Northwest.

Year Completed

1968

Dam Length

205

River Or Stream

Tr-Campbell Creek

Primary Dam Type

Earth

Surface Area

15.2

Hydraulic Height

29

Drainage Area

2.15

Nid Storage

904

Structural Height

27

Hazard Potential

High

Foundations

Soil

Nid Height

29
       
Seasonal Comparison

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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.