Bellevue Detention Pond 165 Reservoir Report

Last Updated: December 14, 2025

Bellevue Detention Pond 165, also known as Northrup Lane Dam Dmp 165, is a crucial infrastructure owned by the local government in Bellevue, Washington.


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Summary

This detention pond plays a key role in flood risk reduction and debris control along the West Tributary Kelsey Creek. Constructed in 1983, this earth dam stands at a hydraulic height of 16 feet and a structural height of 12 feet, with a storage capacity of 73 acre-feet. The dam's primary purpose is to mitigate the risk of flooding in the area, making it a vital asset for the community.

Managed by the Washington Department of Ecology, Bellevue Detention Pond 165 is regulated and inspected to ensure its structural integrity and functionality. With a low hazard potential and a condition assessment of "Not Rated," the dam serves as a reliable barrier against potential water-related disasters. Despite not having a specific spillway type or outlet gates, the dam's design and construction using stone core and rock foundations demonstrate its effectiveness in managing water flow and reducing flood risks in the region.

Located in King County, Washington, Bellevue Detention Pond 165 is a testament to the proactive approach taken by local authorities to safeguard against water-related emergencies. With a drainage area of 0.68 square miles and a maximum discharge capacity of 31 cubic feet per second, this detention pond stands as a critical piece of infrastructure in the community's overall water resource and climate resilience strategy.

Year Completed

1983

Dam Length

80

River Or Stream

West Tributary Kelsey Creek

Primary Dam Type

Earth

Surface Area

12

Hydraulic Height

16

Drainage Area

0.68

Nid Storage

73

Structural Height

12

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

16
       
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.