I honestly don't know how that project maintains any traction. If I recall correctly, last time the Corps of Engineers did an assessment of the proposed benefits from dams in the upper basin, they determined that instead of the 10 feet of water that covered I-5 at Centralia in 2007, with dams in place, there would have been 8 feet of water.
That project maintains traction because local movers and shakers are able to keep the concept alive by spending Other People's Money (OPM; i.e., Thurston Co. & WA state funds, not local), and because they know that the Corps has developed even stupider projects nationally if the political support can be mustered. The second no federal, state, or Thurston Co. money isn't available, and all the costs are on Lewis Co., the Chehalis dam proposal might finally begin to die.
Sg