The U.S. Army Corps of Engineers released its Environmental Impact Statement this fall evaluating the proposed flood retention facility on the Chehalis River above Pe Ell.
The Corps looked at 61 different alternatives for protecting families and communities in the basin from future catastrophic flood damage and found that not one of the other alternatives, without the proposed dam, merited further evaluation. The federal review included proposals to buy-out and remove thousands of families from their current homes, returning the river to its natural condition, floodproofing, changing land use practices, creating emergency bypass for I-5 or building dams in other locations.
The proposed facility is unique in design and proposed operation. It would only function as a dam for a few weeks every seven to 10 years when huge winter tropical storms will create major flood events. During regular operation, fish will be able to pass unimpeded both up and downstream through the open base of the structure. The Corps found that the proposed facility, when combined with raising of the Chehalis-Centralia Airport levee, would protect Interstate 5 in floods as large as the forecasted 100-year flood event. Interstate 5 has been closed through the Twin Cities in flood events of 1990, 1996 and 2007, when the freeway was overtopped for five days.
The Office of the Chehalis Basin is directed by a seven-member board, including two members from Lewis County and representatives from both the Quinault Nation and Chehalis Tribe. Under state law, the board’s responsibility is to find solutions to both catastrophic flood damage and aquatic species decline.
"Both of these problems are getting worse. Since 1986, the floods have gotten larger, and the fishery has been in decline for decades" said Dr. John Henricksen, of Chehalis, who chairs the citizens group One Voice. "After 90 years of pointless government studies followed by no action on both of these problems, the Chehalis Basin process is making real progress with more than 100 local fish and flood projects completed on time and on budget. This proposed facility above Pe Ell is critical to protecting more than 1,300 homes, schools and small businesses, but it is only one piece of a basinwide flood protection and fish restoration strategy."
The Army Corps EIS also evaluated the potential impacts of the proposed flood structure on aquatic species. The Corps’ basinwide look showed that the proportional impact on Coho and fall Chinook salmon and steelhead would be 0 percent, with a 2 percent potential loss of spring Chinook if no mitigation measures were taken.
"The environmental impacts outlined in this federal EIS and the earlier state EIS will have to be avoided, minimized or mitigated, if we proceed to seek a permit," said Lewis County Manager Erik Martin, director of the Flood Zone District, which is the project applicant. "Washington state Department of Fish and Wildlife conducted an extensive search for upper Chehalis river salmon and steelhead between 2013-19. Their published findings show that in 2019, there were three Chinook salmon spawning fish found in the main stem above the city of Chehalis. Only one of those three spawned above the site of our proposed facility. We will need to mitigate or avoid impacts to the fishery. We think we can and then make that a condition of our federal and state permits."
The Office of the Chehalis Basin is also developing an aquatic species restoration plan to restore lost fish habitat along hundreds of miles of the Chehalis river system.
“We see an opportunity to turn a decline in the fishery here to an enhancement,” said former Lewis County Commissioner Edna Fund, a Chehalis Basin Board member. “The modeling forecast near extinction for some of the runs in the coming decades unless dramatic action is taken. We are working to see if we can combine dramatic action to restore a fishery as well as protect families and communities in the basin. We are all seeking a win-win when it comes to flood and fish. All the science shows that we can do both at the same time.”
