Taking steps to improve stretch of I-5 through Nisqually River Valley

By Mark Krulish

Over the next couple of years, we’re taking a closer look at a critical section on Interstate 5.

I-5 through Thurston and Pierce Counties moves goods, people and the US military. It passes directly through the Nisqually River Valley, the traditional home of the Nisqually Tribe, and it is a habitat for threatened salmon and steelhead fish.

Two bridges take I-5 over the Nisqually River – northbound was built in 1937, and southbound in 1967. A lot has changed since then. The population of the South Sound has grown by leaps and bounds and that is expected to continue, which will bring more people traveling throughout the region.

Just as our world has changed, so has our approach to how we build highways. If the Nisqually River Bridges were built today, they would be built in a much different manner. Over the decades, we’ve moved to a mindset where we must also be good stewards of the environment. The work done in 1968 would probably not meet the current environmental regulations passed from the National Environmental Policy Act or the Washington State Shoreline master program. While the roadway is structurally and seismically sound, we now recognize they are not the best structures for the environment. Removal of the fill in the Nisqually Delta requires the replacement of the I-5 Nisqually bridges.

The Nisqually River bridges carry I-5 through the Nisqually River Valley but current environmental
standards mean the bridges must be replaced.

We want to be sure the highway system is ready for any man-made or natural disaster and the environmental impacts on the river and fish, and that starts with a federal Planning and Environmental Linkages (PEL) study.

This phase of the study focuses on I-5 from Marvin Road to Mounts Road (Exits 111 to 116 in Thurston and Pierce counties), with a Focused PEL to consider additional technical analyses and stakeholder input.

The state legislature has set aside $75 million to start working on a project on I-5 through the Nisqually River Delta. This funding allows us to look at ways to improve mobility between Marvin Road and Mounts Road for all types of travelers. We’ll explore a preliminary design for a new bridge and look at any parcel of land we might need to acquire to address flood risk.

This stretch of I-5 through the Nisqually River Valley is being studied as we look to make environmental
 and mobility improvements to the area.

Part of that funding also goes towards three roundabouts on State Route 507, which will be a vital alternative route in the event of a disaster affecting I-5.

We may adopt the Purpose and Need – a statement that describes why the project is necessary – and identified alternative(s), which are determined during this process, into the National Environmental Policy Act environmental review. Doing this work now will help speed up the NEPA process.

We expect to learn a lot more about how people use this corridor through this study, and we’ll share updates as we have them. Keep up to date with the latest news on our project page.