Lewis County flood authorities on Monday briefed residents and stakeholders on a proposed flow-through flood retention facility intended to reduce catastrophic flooding across the Chehalis Basin and protect communities downstream from Centralia to Aberdeen.

The Chehalis River Basin Flood Control Zone District presented updated design work, new environmental mitigation measures and modeled benefits for the structure, which is designed to operate only during extreme events while allowing normal fish passage the rest of the time.

“The revised draft EIS was released on 11/20/2025,” said Kathy Burneman, project manager for the Flood Control Zone District. “Comments are due 02/04/2026.” She listed in-person and online hearings the district will support, including an in-person hearing at Centralia College on Jan. 6 and an online hearing on Jan. 8, plus an additional in-person session in Aberdeen around Jan. 13.

Project proponents said up-front modeling shows the facility would temporarily hold on the order of 62,000 acre-feet of floodwater at the proposed site and that the state’s initial analysis estimates more than 2,600 valuable structures could be spared flood damage under modeled scenarios. Jay Vanderstoop, a board member and local resident speaking for the district, said the modeling indicates basin-wide benefits "if we can hold 62,000 acre-feet of floodwater ... there's the benefit all the way down." The presenters said the models are intended to show basinwide effects, not to suggest benefits are limited to any single community.

Officials described fish-protection measures and construction staging intended to reduce environmental harm. Kathy Burneman said the project now includes a phased, mostly dry construction approach and a comprehensive mitigation plan with vegetation management, habitat restoration and planting downstream parcels to increase river shading; staff reported outreach to about 131 downstream landowners who indicated willingness to participate in shading plantings that together would cover roughly 16.8 miles of river.

Eric Eisenberg, deputy district administrator, described the fish-handling backup for extreme events: "The amount of water that flows through the facility when we're closing to hold back floodwaters is an average winter flow, which is about 300 cubic feet per second," he said, explaining that high backwater could make normal volitional passage difficult and that a trap-and-haul system would be used when needed.

District staff described design differences from earlier plans. Presenters said the updated design avoids a conventional, year-round barrier: most years the gates would remain open and fish could move through conduits; the structure would only restrict flow under rare, severe events. The district emphasized that fish passage standards set by state agencies must be met in any permit process.

On costs and schedule, presenters cited engineering estimates with a wide range. "1.3 to 2.3 is their current range," Jay Vanderstoop said when discussing HDR's cost estimate, which staff characterized as roughly $1.3 billion to $2.3 billion for the retention facility; they added that habitat work across the basin would add substantial additional costs. Engineers told the group to plan conservatively on roughly seven years from the current stage through EIS and permitting into construction, but officials said permitting could take longer (presenters suggested planning for eight to 10 years and noted litigation could extend the schedule further).

District staff and local officials also highlighted practical preparedness and monitoring improvements. Multiple speakers praised expanded river gauges and dashboards that provide near-real-time updates (some gauges report every 15 minutes), credited staff maintenance for reliability, and said better monitoring reduced uncertainty during recent storms.

The revised draft environmental impact statement is under state and federal review. The district encouraged public review and comment through the Department of Ecology process and said mitigation proposals submitted by the district will be evaluated during permitting and further analysis.

Next steps: the district said it will accept public comments through the EIS comment period, continue technical and agency review, and participate in the scheduled hearings in early January. No formal action or vote was taken at the briefing; the session was informational only and recorded for public posting.

Who spoke: Scott Brummer (chair of the Flood Control Zone District) opened the briefing; Kathy Burneman (project manager) presented mitigation and process updates; Jay Vanderstoop (board member and local resident) described modeling and benefits; Eric Eisenberg (deputy district administrator) explained fish-passage operations and trap-and-haul procedures. Additional local officials, Port staff, council members and community members participated in Q&A and public comment.