TRPC eyeing a big portion of $75 million Move Ahead Washington fund to fix I-5 Nisqually River bridges

Thurston Regional Planning Council Executive Director Marc Daily wants over $54 million of the $75 million appropriations from the Move Ahead Washington fund to fix the Nisqually River Delta bridges.

Gov. Jay Inslee signed March this year the Move Ahead Washington a 16-year transportation packagewhich with almost $17 billion investment on preserving and maintaining existing infrastructure, expanding reliable and affordable transportation options, building a new I-5 bridge, and replacing aging ferry vessels.

From 2018 to 2020 the Washington State Department of Transportation worked with the Thurston Regional Planning Council (TRPC) to completed a study titled, I-5: Tumwater to Mounts Road Corridor Study. The 316-page study is available at this link.

Since 2017, he said the Thurston County has received funding of $500,000 for the project that would improve the transportation system along I-5 with the Planning and Environmental Linkages (PEL) study, concluded in March this year.

Thurston County also received $5 million to do the project's National Environmental Policy Act review.

He added the $75 million from Move Ahead Washington would build improvements on the I-5 transportation system.

Part of the PEL study is identifying a long-term strategy for the Nisqually River bridges, including ecosystem benefits for salmon habitat and flood control. 

"When we first started looking at this, it was about [traffic] congestion. But as we got into this, the Nisqually Indian Tribe was the first to point out the issue of the Nisqually River," he told the Olympia councilmembers on Tuesday, June 7.

According to the PEL report, the Nisqually Indian Tribe has expressed concern that I-5 causes an unnatural restriction to natural flow of the Nisqually River into the delta. There are eight bridges along the stretch of I-5.

Citing the U.S. Geological Survey (USGS) Hydrology Study, Daily said I-5 causeways and bridges are at risk of flooding.

"Nisqually River is a high energy stream and that energy has got to go somewhere," Daily said, adding, "the Nisqually River started heading a channel towards I-5."

The USGS study predicted higher peak river flow due to climate change and seal level rise, which would exacerbate flooding at I-5, mobilize more sediment that could raise the river bed elevation.

The study – subject for peer review - further stated that the bridges are not climate change resilient and impact the processes that form and maintain habitat for important fish and wildlife species, including salmon and steelhead.

"Nisqually River will cut its channel to I-5 within 17 to 25 years, and that is if we don't have major [flooding] events like what we saw in 1996- 1997. If we do, that risk is much higher. It could happen much sooner," he said at the recent Olympia city council meeting. 

Salmon habitat

I-5 is choking the channel, according to Daily.

"That channel where saltwater and the freshwater mix is incredibly important to salmon as they transition from being young freshwater animals to juvenile and eventually adult saltwater animals," Daily added.

He said there should be a bigger mixing area where salmon could grow healthy. "Study after study has shown that their survival to adulthood and to spawn is much higher when they are fit when they leave their watershed origin."

"This is a huge issue for the Nisqually Indian Tribe," Daily added.

Alternate routes

According to Daily, motorists rely heavily on I-5 and do not have many viable alternatives. "We are constrained by Puget Sound to the north and JBLM (Joint Base Lewis-McChord) to the south and east.

He said they looked at Highway 507, which could be one of the main alternate routes.

"Our modeling showed that if we are to put a roundabout at the intersection of State Route 702, at the intersection with Vail Road and within Yelm at the intersection of Bald Hill Road, it dramatically improves the function of that roadway in the vehicles and people and goods and services that can move through the area,’’ explained Daily.

The PEL study also recommended building new roundabouts on State Route 507 and Centre Street, SR 507 Sussex Avenue E/SR 507 and Old Highway 99, Steilacoom Road and SR 510, Mounts Road interchange on both northbound and southbound ramps.