The Chehalis River Basin has historically seen a lot of flooding. Officials want to reduce major flooding risks.

The Chehalis River Basin has historically seen a lot of flooding. Officials want to reduce major flooding risks.

Flickr Creative Commons: Andy Karmy

One of the worst floods in Southwestern Washington’s Chehalis River Basin infamously separated parts of northern and southern Washington. Interstate 5 was inundated. Homes and businesses filled with water. Transportation stopped.

“So the flooding is quite real. And with that flooding comes damage,” said Curt Hart, a spokesman with the state Department of Ecology.

He says over the past 30 years, flooding in the area has gotten worse and it’s only expected to increase as the climate changes and more precipitation falls as rain, instead of snow.

Officials want to prevent the kind of damage seen in those 2007 floods.

To do that, the Chehalis River Basin Flood Control Zone District wants to build a floodwater retention structure on the river near the town of Pe Ell. Normally the river would simply flow through the structure.

“But if we had a major flood, gates could close. Floodwater could be stored,” Hart said.

The structure could temporarily store up to 65,000 acre feet of floodwater, which would be released downstream as soon as it was safe for people and for habitat.

“The structure wouldn’t be there to hold back every flood, really just a major flood,” Hart said. “Nor could the structure prevent floods everywhere in the Chehalis River Basin. It’s really looking at different strategies to prevent damages from floods.”

The plan also seeks to raise the levee at the Chehalis-Centralia Airport.

“So not only are we looking at protecting critical transportation corridors, but also people’s homes, people’s farms and also the aquatic habitat that everyone depends on in the basin,” Hart said.

The Washington Department of Ecology and the U.S. Army Corps of Engineers are accepting public comments on the plan through Oct. 29.

Public comments like, “environmental issues that should be studied, project alternatives, probable adverse significant impacts,” said Patricia Graesser, spokeswoman for the Army Corps.

Officials will also conduct two open house public meetings in:

  • Montesano, from 5 to 8 p.m., Oct. 16, at the Montesano City Hall, 112 N. Main St.
  • Centralia, from 5 to 8 p.m., Oct. 17, at Centralia College, Bowman Rotary Banquet Rooms, 600 Centralia College Blvd.