Issaquah Highlands Npe Pond Reservoir Report

Last Updated: December 14, 2025

Issaquah Highlands Npe Pond, located in Issaquah, Washington, serves as a crucial element in flood risk reduction efforts in the region.


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Summary

Managed by the local government and regulated by the Washington Dept of Ecology, this earth dam structure was completed in 2003 and stands at a hydraulic height of 24 feet. With a capacity to store up to 36 acre-feet of water, this pond plays a vital role in mitigating potential flood hazards in the area, particularly during periods of high discharge.

Covering a surface area of 3.1 acres and draining a 0.1 square mile area, Issaquah Highlands Npe Pond is designed to withstand high hazard potential events and has been assessed to be in fair condition as of the last inspection in July 2020. The dam's primary purpose is flood risk reduction, with a normal storage capacity of 11 acre-feet. While the structure has not undergone any modifications over the years, regular inspections are conducted every 5 years to ensure its continued safety and effectiveness in protecting the surrounding communities along NF Issaquah Creek.

With a designated emergency action plan (EAP) review date in December 2021 and a contact frequency of every 5 years, Issaquah Highlands Npe Pond remains a critical component in the region's water resource management and climate resilience strategies. As climate change continues to pose challenges in terms of increased precipitation and extreme weather events, the importance of maintaining and monitoring infrastructure like this earth dam becomes ever more apparent in safeguarding communities and environments against the impacts of flooding.

Year Completed

2003

Dam Length

480

River Or Stream

NF Issaquah Creek - Offstream

Primary Dam Type

Earth

Surface Area

3.1

Hydraulic Height

24

Drainage Area

0.1

Nid Storage

36

Structural Height

24

Hazard Potential

High

Foundations

Soil

Nid Height

24
       
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.