Members of the Chehalis River Basin Flood Authority were among the first people to get an in-depth glimpse at a comprehensive project aimed at protecting the city of Centralia from floodwaters from China Creek, just days before initial work begins on a portion of that project.
Centralia Public Works Director Kahle Jennings gave the group a 30-minute presentation on mitigation efforts in the Centralia area that hope to store rainfall runoff and prevent it from heading down China Creek, flooding primarily downtown areas and portions of Yew Street.
Significant rainstorms and flood events in the past have swelled China Creek to the point of flooding downtown, particularly around the Eubanks Glass building along Main Street. Such flooding also creates a “backwater” effect along Yew Street, flooding homes in a particularly vulnerable area.
“Generally, two and a half inches of rainfall is enough to generate surface runoff that historically exceeds capacity of China Creek,” Jennings said.
Jennings showed two locations that the city has identified as possible runoff storage locations: the Agnew Mill Ponds and an area along McAtee Road. A landowner had donated 28 acres near the Agnew Mill Ponds to the city, valued at $1 million, for the project.
The city had planned to build berms 2 feet high on that property, and would have liked to go higher, but Jennings said a permit for a dam would be required.
“The thought was that if we can store some water just long enough there, we might be able to control these flood impacts,” Jennings said.
Jennings pointed out that although the projects at the Agnew Mill Ponds and McAtee Road could help, they wouldn’t solve the problem completely. Jennings told the Flood Authority that he spoke with Mark White, director of natural resources for the Confederated Tribes of the Chehalis Reservation, who invited him to take a trip to Johnson Creek in Portland — a waterway that was notorious for overrunning its banks and threatening nearby homes and businesses during flood events.
“They took a meadowland, and instead of creating a structure to store floodwater, they created natural storage areas so the water spills into them and fills them up,” Jennings said. “It’s a good concept of a non-structural project.”
The city of Centralia in late May approved the purchase of 28 acres of land for $212,000 in the 100 block of Lundberg Road. The area, in the upper China Creek watershed, could prove to be a prime area to undertake a project similar to the one along Portland’s Johnson Creek, Jennings said.
Jennings told The Chronicle in a later conversation that the project in that area will not only serve as a flood mitigation project, but as a fish habitat project that will also double as a natural area. He hopes to install walking trails on the 25-acre plot of land that now belongs to the city of Centralia.
“I’d like to start construction next summer, and I think it’s achievable,” Jennings said. “The permitting process will determine whether or not we can actually do that.”
The money for the purchase came from $460,000 that the Washington State Department of Transportation gave the city of Centralia as part of impact mitigation for the Interstate 5 widening project.
“It’s going to happen in the next couple years, and it has the support of the city council and the Chehalis Tribe,” Jennings said. “Next week they’re going to mow the field, then they’ll do a topographical survey and look at just how much water we can store.”
Members of the Flood Authority reacted favorably to the idea, with Thurston County Commissioner Karen Valenzuela commenting that it was a “tremendous” plan. Napavine City Councilor Lionel Pinn said Centralia’s proposal got the wheels turning in his head about projects in the Napavine area to mitigate flood risks along the Newaukum River.
“It makes us think about our own projects in a lot of ways,” Pinn said.
Jennings went back to the money WSDOT gave the city, noting it was that cash that enabled the city to take action.
“That energized us,” Jennings said. “We went from ‘study’ to ‘do.’”
Christopher Brewer: (360) 807-8235