Increasingly intense flooding puts more people in danger.
The Chehalis River Basin Flood Control Zone District (Flood District) is seeking to construct a unique flood-control dam and temporary reservoir on the Chehalis River near Pe Ell and make improvements to the levee around the Chehalis-Centralia Airport.
Under the Flood District’s proposal, waters in the Chehalis River would flow freely through the dam structure unless a major flood occurs in the upper Chehalis River Basin, triggered by rainfall in the Willapa Hills. The dam would then close its gates to temporarily hold back floodwaters to reduce flood-related damage from Pe Ell to Centralia. Water would be safely released later. (See the vicinity map.)
The proposed project also includes airport levee improvements to protect the Chehalis-Centralia Airport, local businesses, and area transportation from major flood damage. In addition to raising the existing levee around the airport, about 1,700 feet of Airport Road would also be raised.
Current status: under review
Washington’s Department of Ecology and the U.S. Army Corps of Engineers are conducting environmental reviews of the proposed dam under the State Environmental Policy Act and National Environmental Policy Act. These reviews are designed to analyze how the proposed dam is likely to adversely affect the environment and the measures being proposed to offset, or mitigate, those impacts.
View more information about the state and federal reviews.
What is the Flood District?
As result of the devastating Chehalis River floods in 2007 and 2009, the Lewis County Board of County Commissioners formed the Chehalis River Basin Flood Control Zone District (Flood District) to find solutions to reduce flood risks, protect Basin communities, and preserve the ecosystem benefits the Chehalis River system provides.
The Chehalis Basin Board is assessing whether the proposed dam should be incorporated into the long-term Chehalis Basin Strategy to help reduce flood-related damage in the upper part of the Chehalis River Basin. The Board will use the findings in the state environmental review, as well as other information, to inform their recommendations. Their decision is anticipated in early 2026.
The Board is also considering several other options for large-scale flood damage reduction, including the Local Actions Non-Dam Alternative. Board members will decide which projects to move forward after the state environmental review of the proposed dam is complete.
Watch past webinar recordings about the proposed flood-control dam:
Community Update: Proposed solutions for large-scale flood damage reduction (Oct. 2024)