West Richland Sewage Lagoon North Reservoir Report

Last Updated: December 14, 2025

West Richland Sewage Lagoon North, located in Benton County, Washington, is a key water resource managed by the local government.


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Summary

This sewage lagoon, completed in 1961, serves as an offstream tributary to the Yakima River and covers a surface area of 35 acres with a storage capacity of 75 acre-feet. The lagoon is regulated and inspected by the Washington Department of Ecology, ensuring compliance with state water quality standards and enforcement measures.

The dam at West Richland Sewage Lagoon North is an earth-fill structure with a hydraulic height of 6.5 feet, providing essential wastewater treatment and storage capabilities. The lagoon has a significant hazard potential and is assessed to be in fair condition as of the last inspection in April 2016. Emergency action plans are in place to address any potential risks, with regular inspections conducted every five years to ensure the structural integrity and functionality of the facility.

Given its critical role in wastewater management for the West Richland community, the Sewage Lagoon North serves as a vital component of the local water infrastructure. With ongoing state oversight and maintenance efforts, this facility continues to play a crucial role in safeguarding water resources and supporting the region's environmental sustainability goals.

Year Completed

1961

River Or Stream

Tr-Yakima River-Offstream

Primary Dam Type

Earth

Surface Area

35

Hydraulic Height

6.5

Drainage Area

2

Nid Storage

75

Structural Height

6.5

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

7
       
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.