CHEHALIS  – 

A revised draft environmental impact statement looks at the potential impacts to fish, habitat, water quality and nearby communities from a proposed project to reduce flood damage in the Chehalis River basin. The Washington Department of Ecology is seeking public input on the analysis through Feb. 4, 2026.

The environmental assessment looks at a combined proposal to build a flow-through dam on the Chehalis River near Pe Ell to control flooding and make changes to the Chehalis-Centralia Airport levee. The proposed projects could become important parts of a larger plan to reduce flood-related damage and restore aquatic habitat in the river basin. Severe flooding has repeatedly damaged homes, farms and businesses, scoured stream channels and closed U.S. Interstate 5.

The flood-damage reduction project is being considered for inclusion in the larger Chehalis Basin Strategy. That strategy is a long-term action plan for reducing flood-related damage and recovering salmon and other aquatic life throughout the 3,400 square mile Chehalis River basin in southwest Washington.  

Ecology’s revised draft environmental assessment is not a permit, nor does it approve or deny the proposal. Instead, it assesses how the project would impact the area, providing critical information for decision-makers such as the independent Chehalis Basin Board to consider. The board is composed of members representing the Chehalis River Basin Flood Authority,  Quinault Indian Nation, Confederated Tribes of the Chehalis Reservation and agricultural, environmental and economic interests in the basin. The board oversees the ongoing development of the strategy and will make a decision whether to pursue the flood- damage reduction project.

“This evaluation weighs the trade-offs between flood protection and impacts to the environment, fish and other resources,” said Bobbak Talebi, Ecology’s Southwest Region Director. “Our goal is to give the Chehalis Basin Board the in-depth analysis it needs to help assess whether to include the project in the long-term Chehalis Basin Strategy that they will recommend to the Legislature in 2026.”

The major feature of the project, the proposed flow-through dam – called the “flood retention facility” in the environmental impact statement – isn’t a dam in the traditional sense. Most of the time, the Chehalis River would flow through the structure unimpeded. During a major flood, however, the gates could be closed to protect Pe Ell, Centralia, Chehalis and other downstream communities, creating a temporary reservoir storing up to 62,000 acre-feet of water. Once flooding recedes, that reservoir would be gradually emptied over the course of several weeks.

Ecology’s analysis found that the project would reduce flooding in the basin but with climate change, flood risks would persist during extreme conditions in the mid and late century. The analysis also found that the project would place additional burdens on salmon and other aquatic species and their habitat, even with the fish passage and other mitigation measures. Over the last century, salmon populations in the Chehalis basin have declined due to a variety of factors including habitat loss, increased water temperatures and low stream flows.

The project could also affect archaeological sites and cultural resources for nearby Tribes.

The proposal, which comes from the Chehalis River Basin Flood Control Zone District, makes several significant changes to an earlier design proposed in 2019. Ecology released a draft environmental analysis of that plan in 2020. Changes to the proposed project include relocating the flow-through dam structure upstream 1,000 feet, improving fish passage through the project, and adding mitigation options to address the project’s impacts. These changes required Ecology to revise its original environmental analysis.

Ecology considered all comments submitted during the first draft when evaluating the revised project design.

Ecology plans to issue a final environmental impact statement in 2026.

More information

• Revised draft environmental impact statement of proposed Chehalis River Basin Flood Damage Reduction Project – Washington Department of Ecology

Public input

You can submit comments on the revised draft environmental impact statement through Feb. 4, 2026.

By mail:

SEPA Revised Draft EIS for the Chehalis Flood Damage Reduction Project
c/o Bobbak Talebi
P.O. Box 47775
Olympia, WA 98504-7775

Online:

By filling out and submitting our comment form.

In person at an open house and public hearing:

• Tuesday, Dec. 9, 2025
• Tuesday, Jan. 6, 2026

Both open houses will be held in Centralia starting at 5:30 p.m., with public hearings to follow from 6 to 8 p.m. at:

Centralia College
Rose Bowman Banquet Hall, TransAlta Commons
615 W. Pear St.
Centralia, WA 98531

Online public hearings:

• Thursday, Dec. 11, 2025, from 6 to 8 p.m. on Zoom
• Thursday, Jan. 8, 2026, from 6 to 8 p.m. on Zoom

The U.S. Army Corps of Engineers is conducting a separate environmental review of the Flood District’s proposal under the National Environmental Policy Act (NEPA). They plan to release this federal review in 2026.