From the Oregonian Breaking News blog:
http://blog.oregonlive.com/breakingnews/2007/12/reports_fix_for_flooding_probl.html

In fact, there was actually $30 million to control flooding from the river in the big nickel-a-gallon gas tax increase approved by Washington voters in 2003. But as the Times explains,Congress has failed to approve the federal share of the project while the cities of Centralia and Chehalis “have struggled to agree on needed flood controls.” While the project would have protected I-5, the cities would have still been vulnerable to flooding, so they didn’t want to assume the maintenance costs. As a result, Lewis County sent a letter to the Corps of Engineers last year rescinding its support for the project.

They go on to mention that Corps of Engineers priorities shifted funding to Katrina-related repairs and Iraq/Afghanistan, so even if Chehalis would have wanted to move foward, they couldn’t have.

I-5 is still closed, and Dept of Transportation says it will continue to be closed for several days.

From OPB:

Normally more than 50,000 cars and trucks would use that portion of I-5 daily. It’s estimated the closure is costing truckers $4 million a day.