Not a fan of dams and the mitigation, the Wynoochee is great example, but if one wants to argue against something it is best to put emotion aside and use facts. Below is a C&P of info and one can see it is I 5 not the businesses or locals driving this but it is for them a don't look a gift horse in the mouth time. Also the effects on fisheries are outlined. Now one should not buy that as gospel because all things have unintended consequences. Take the Wynoochee it ended up being the mitigation for areas above the dam were not the greatest loss but rather down stream. As a flood control dam it has been of great value but by controlling the high water it reduced the natural habitat building processes. Then WDFW has failed to implement the full mitigation required for 25 years. Always be a little concerned about mitigation with WDFW's dubious record in the Chehalis Basin.

Why & How:
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.

"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."

And The Fish:
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."

So if your going to provide input " you dirty rat " approach will fail. There are ample examples of unintended consequences and mitigation failures ( in the Chehalis Basin ) by WDFW and others to allow for a rational pointed argument opposing.