Addressing flood risk on I-5 in Nisqually basin now a priority for Pierce County Council
Pierce County has prioritized finding money to repair a 2.5-mile stretch of Interstate 5 that could flood within the next 20 years.
On Monday, the Pierce County Council discussed the future of the Interstate 5 bridge that crosses the Nisqually River and its current impacts on the environment, military and traffic.
Council Chair Derek Young (D-Gig Harbor) said the county needs to press harder finding money to repair the bridge.
“I didn’t realize the degree of alarm I should have had,” Young said Monday’s council study session. “This is a much more critical, short-term issue than I thought. So I apologize for whatever ignorance that I had, but I think you got my attention.”
The Nisqually Tribe of Indians’ natural resources director David Troutt and South Sound Military & Communities Partnership executive director Bill Adamson presented at the study session. The two entities have spearheaded efforts to fund a repair project on Interstate 5.
Council members were supportive of the project and promised more county involvement moving forward.
In December, The News Tribune published a three-part series on traffic, environmental and military concerns regarding the stretch of Interstate 5 that crosses the Nisqually River delta. Between climate change and construction design, the 2.5-mile stretch of the highway south of Joint Base Lewis-McChord between Pierce and Thurston counties is at risk of flooding.
The state filled in most of the space underneath the bridge in the 1960s, creating a causeway. The majority of the Nisqually River passes through the largest opening left, which is about 180 feet wide.
The dirt, rocks and cement that create the causeway are are acting as a dam to the river’s natural course. In the last 50 years, the causeway has altered the course of the river and magnified the risk of water spilling onto Washington’s vital highway.
Initial models by the U.S. Geological Survey predict a flood could occur within 20 years.
“The timing and extent that I-5 is likely to become vulnerable to the projected changes in sea-level rise and stream flows were evaluated in terms of water levels that will disrupt access to the highway and potentially cause danger to human safety,” USGS scientist Eric Grossman told The News Tribune in September.
This construction decision accelerated impacts to the environment, like salmon habitats. Gabe Madel, the district biologist for the Washington state Department of Fish and Wildlife who oversees the Puyallup and Nisqually rivers spoke to The News Tribune of the Nisqually River’s importance for the fish.
“It’s the only intact estuary in the Puget Sound,” Madel said. “They head south then turn around and migrate north on their typical journey out to the actual Pacific. Just from that standpoint alone, it’s a pretty important habitat in South Puget Sound.”
Joint Base Lewis-McChord is five miles from the bridge, causing concern among military officials. A flooded highway would prevent about 40 percent of military personnel who live south of the bridge from getting to the base, causing a “national security risk.”
A preliminary cost estimate by the Nisqually Tribe and South Sound Military & Communities Partnership puts the price of repair at $4.2 billion to:
replace the bridges across the Nisqually River,
elevate the highway across the Billy Frank Jr. Nisqually National Wildlife Refuge,
widen Interstate 5 from three lanes to up to five lanes each way,
expand the railroad overpasses east of the bridge
Adamson and Troutt have proposed that legislators consider an alternative route to the interstate. They have estimated that another route between Mounts Road and Tumwater would cost $125 million: $100 million to develop options for the road , $19 million for roundabouts in Yelm, and $6 million for the right of way.
“The numbers were coordinated with representatives from WSDOT as ballpark estimates,” Adamson said in an email. “There are no construction costs included in the $125 million.”
Adamson provided The News Tribune more detail, saying that the proposal would also add much needed capacity to handle growing traffic concerns.
“There are no good alternatives to I-5, other than [state Route] 507 going through Yelm,” he said in the Monday meeting.
Council member Ryan Mello (D-Tacoma) said finding funding for the Nisqually project as a whole should be the county’s highest priority.
“This is just a super significant project that we must really prioritize ties for regional, state and federal investments,” he said.
Funding for the Nisqually project has become a county priority for Washington’s 2022 Legislative session. Young and other council members also will head to Washington, D.C., to meet with congressional representatives next week.
“Certainly we will bring that as one of our agenda items,” he said. “Obviously, what happens on I-5 affects the entire state, so we should probably be talking with our colleagues throughout the region to say you need to be advocating for this too. Because if we lose this segment, it’s not Pierce County that suffers, it’s the entire region.”
This story was originally published February 8, 2022 at 5:00 AM.
