Tapps Lake Dike No 2a Reservoir Report

Last Updated: December 15, 2025

Tapps Lake Dike No 2a is a crucial structure located in Pierce County, Washington, designed to divert water from the White River.


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Summary

Constructed in 1911, this earth dam serves primarily for recreational purposes, with a maximum storage capacity of 20,000 acre-feet and a normal storage of 18,000 acre-feet. With a hydraulic height of 9 feet and a structural height of 9 feet, the dam spans 350 feet in length, creating a surface area of 2,570 acres.

Managed by the Washington Department of Ecology, Tapps Lake Dike No 2a is regulated and inspected regularly to ensure its safety and functionality. The dam is classified as having a high hazard potential, although its condition assessment as of February 2018 was deemed satisfactory. Despite its age, the structure has been well-maintained and meets regulatory guidelines, with emergency action plans in place and regularly updated.

Located in Auburn, Washington, Tapps Lake Dike No 2a falls under the jurisdiction of Congressional District 08 and is overseen by Representative Kim Schrier. With its vital role in water diversion and recreation, this dam serves as a testament to successful water resource management in the region, highlighting the importance of infrastructure for both environmental and recreational purposes in the face of changing climate conditions.

Year Completed

1911

Dam Length

350

River Or Stream

Diversion from White River

Primary Dam Type

Earth

Surface Area

2570

Hydraulic Height

9

Drainage Area

9.7

Nid Storage

20000

Structural Height

9

Hazard Potential

High

Foundations

Soil

Nid Height

9
       
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.