State Environmental Review

State Environmental Review of Proposed Chehalis River Basin Flood Damage Reduction Project

The Chehalis River Basin Flood Control Zone District (FCZD) is proposing to construct a flood retention dam and associated temporary reservoir on the Chehalis River near Pe Ell, and make changes to the Chehalis-Centralia Airport levee. Ecology is conducting an environmental review of this proposed project under the State Environmental Policy Act (SEPA) through an Environmental Impact Statement (EIS).

The FCZD’s objective for their project is to reduce damages from major floods from Pe Ell to Centralia triggered by rainfall in the Willapa Hills. The Airport levee changes would raise and widen the Chehalis-Centralia Airport levee and nearby roads to improve the levee protection level during catastrophic floods. The project is not intended to address flooding in all parts of the Chehalis River basin and would not stop regular annual flooding.

Proposed Chehalis River Dam

Status of the EIS

Since the release of the draft EIS is 2020, the FCZD (project applicant) revised the project design. Ecology received a revised project description in April 2024 and is currently reviewing the new information and will now restart the environmental review process.

Ecology will develop a revised draft EIS before developing the final EIS. The draft is anticipated in the fall of 2025 and the department will conduct a comment period to take public input on the revised draft environmental study. Ecology anticipates completing a final state EIS in spring 2026.

The final EIS will include revisions based on the public comments we received for the 2020 draft EIS, additional modeling and impact analyses for the new design and comments we receive on the revised draft EIS next year. It will include a range of potential impacts based on high and medium climate-change models from the University of Washington Climate Impacts Group. The final EIS report also will provide responses to the substantive comments we received on the draft and revised draft EIS documents.

Ecology will continue to coordinate with other state agencies, U.S. Army Corps of Engineers, and the applicant throughout this process.

An EIS does not approve or deny a project or make a decision on permits. The final EIS will provide information for the public and decision-makers, such as the Chehalis Basin Board and permitting agencies.

2020 Draft EIS

Ecology released a draft state Environmental Impact Statement (EIS) in February 2020 that analyzed how the proposal is likely to affect the environment under the State Environmental Policy Act (SEPA). Ecology’s focus sheet has an overview of the findings of the 2020 draft state EIS. Note that some of the impacts identified in the 2020 draft will change based on the new analysis for the revised project design.

A comment period for the draft state environmental review of the proposed Chehalis River Basin Flood Damage Reduction Project was held from February 27 to May 27, 2020, and two public meetings were held in April 2020. The presentation of the draft EIS shown at the public meetings is available as slides or with audio. All comments are valued equally.

When developing the final state EIS, Ecology will consider comments received during the 2020 comment period in addition to new comments that will be collected for the revised draft EIS in fall 2025.

Comments on the draft EIS have been arranged in categories solely for ease of access and downloading. 

Impacts Identified in the 2020 Draft Study

Ecology’s original draft EIS identified likely significant environmental impacts from the Flood District’s project as well as alternatives. Ecology looked at 17 different environmental elements including impacts to air quality, cultural resources, earth, environmental health and safety, environmental justice, fish and aquatic species and habitat, land use, noise, public services and utilities, recreation, transportation, tribal resources, visual quality, water, wetlands, and wildlife species and habitat.

Under Ecology’s analysis, the project would reduce flooding to buildings and infrastructure, including U.S. Interstate 5. It would have significant adverse effects, mainly along the Chehalis River in the area above the flood retention dam and below the structure to Rainbow Falls. These include:

  • Reducing spring- and fall-run Chinook salmon, coho salmon, and steelhead trout
  • Reducing native aquatic species such as lamprey and mussels
  • Reducing wildlife such as amphibians
  • Degrading habitat on land, and in water and wetlands
  • Degrading river and stream water quality
  • Eliminating access for recreational fishing and whitewater boating
  • Increasing greenhouse gas emissions
  • Impacting tribal and cultural resources

Several impacts from the proposal would be unavoidable unless measures to offset them are determined to be feasible and meet regulatory requirements. This would be determined during future permitting processes including local and Tribal governments, and state and federal agencies.

Should the project move forward, there are nearly 40 local, state, and federal authorizations, approvals, and permits that would be needed.

EIS Analysis Integrates Climate Change

Since climate change will drive more frequent, higher flood levels, and steeper declines in fish runs in the Chehalis River basin in the future, Ecology integrated climate change in their analysis of future conditions where the proposed flood retention dam would operate.

Project Alternatives Analyzed

The study analyzed an alternative based on local and nonstructural actions that could help retain flood waters and reduce flood-related damage. It also analyzed what is known as a “no action” alternative. Both alternatives examine what would happen if the flood retention facility is not built and no changes are made to the Chehalis-Centralia Airport levee.

Summary Available of 2018 State EIS Scoping

The public scoping period for the state EIS was held from September 28 through October 29, 2018, which is the first step in the EIS process. Public input on the scope of the SEPA EIS helped identify project alternatives, probable significant adverse impacts, potential mitigation measures, and permits or approvals that may be required. Ecology and the U.S. Army Corps of Engineers (USACE) held a joint SEPA-NEPA EIS scoping period—including two public hearings—to receive input regarding the scope of the state EIS. The SEPA EIS Scoping Summary Report provides a summary of public outreach and scoping comments.

Contact Us

Environmental Review Contact

Meg Bommarito
Ecology SEPA EIS Project Manager
(425) 681-6236

Media Contact

Brittny Goodsell
Ecology Communications Manager
(360) 280-3704

Equal Access

To ensure equal access to materials, Ecology will provide auxiliary aids/services to persons with disabilities. Please call (360) 407-6831 with any requests. Persons with hearing loss and speech disability can contact 711 for the Washington Relay Service. Persons with a speech disability may call TTY at (877) 833-6341. All meeting-related requests must be received 72 hours in advance.