Panther Lake Detention Dam Reservoir Report

Last Updated: December 14, 2025

Panther Lake Detention Dam, also known as Panther Lake Ballfield Dam, is a private water management structure located in Federal Way, Washington.


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Summary

Completed in 1994, the dam serves the primary purpose of flood risk reduction in the area. With a hydraulic height of 12 feet, the dam has a storage capacity of 339 acre-feet and can handle a maximum discharge of 650 cubic feet per second, making it a critical asset for managing water flow in the region.

Situated offstream, the Panther Lake Detention Dam is regulated by the Washington Department of Ecology and undergoes regular inspections to ensure its structural integrity. The dam's hazard potential is classified as high, but its condition assessment as of February 2017 was rated as fair. Despite its solid performance, the dam has not been modified over the years, and there is no emergency action plan in place as of the last update in 2007.

For water resource and climate enthusiasts, Panther Lake Detention Dam offers a fascinating example of private infrastructure dedicated to flood risk reduction. Its strategic location and design contribute to the overall water management efforts in King County, Washington, highlighting the importance of such structures in mitigating the impacts of extreme weather events and protecting local communities from potential flooding.

Year Completed

1994

River Or Stream

Offstream

Primary Dam Type

Earth

Hydraulic Height

12

Drainage Area

2.05

Nid Storage

339

Structural Height

12

Hazard Potential

High

Foundations

Soil

Nid Height

12
       
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.