Longview Sewage Lagoon No 1 Reservoir Report

Last Updated: December 14, 2025

Longview Sewage Lagoon No 1, located in Longview, Washington, is a vital water resource managed by the local government.


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Summary

The lagoon, completed in 1986, serves as a key component in the treatment and disposal of sewage in the area. With a storage capacity of 207 acre-feet and a surface area of 28 acres, it plays a crucial role in maintaining water quality in the region.

This Earth dam structure, with a hydraulic height of 9 feet and a structural height of 4 feet, helps regulate the flow of water from Tr-Coal Creek Slough-Offstream. Despite its low hazard potential and not being currently rated, the Longview Sewage Lagoon No 1 is subject to regular inspections, enforcement, and permitting by the Washington Department of Ecology. With a drainage area of 0.04 square miles and a maximum discharge of 8 cubic feet per second, this facility plays a significant role in protecting the environment and public health.

As an essential part of the local water infrastructure, Longview Sewage Lagoon No 1 demonstrates the commitment of the community to effective sewage management. With its state-regulated status, regular inspections, and low hazard potential, this lagoon serves as a model for responsible water resource management. Its location in Cowlitz County, Washington, showcases the importance of sustainable practices in maintaining the quality of the region's waterways.

Year Completed

1986

Dam Length

3250

River Or Stream

Tr-Coal Creek Slough-Offstream

Primary Dam Type

Earth

Surface Area

28

Hydraulic Height

9

Drainage Area

0.04

Nid Storage

207

Structural Height

4

Hazard Potential

Low

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.