State money needed now to create a vision for I-5’s future in the Nisqually Delta

The Nisqually Delta is at risk again.

In the past, the risks to the Delta were from proposed developments: Seattle thought about using it as a garbage dump, Tacoma wanted to build a deep-water port complete with oil tankers, and the Port of Olympia had an idea about an aluminum plant.

We have beloved Olympia civic leader Margaret McKenny (1885-1969) to thank for being the first to organize citizen opposition that prevented those projects. Since her death, the Nisqually Delta Association has successfully prevented others.

Today, the Nisqually Delta is home to the Billy Frank Jr. Nisqually National Wildlife Refuge, and a pastoral valley with a river running through it.

Now the risk facing that beautiful valley comes from a river that tends to wander, a trend towards more rain and less snow, and sea level rise. Those three factors — all features of climate change — mean that Interstate 5, which is a giant dam across the valley, will be in the way as waters rise on both sides of it.

The wandering Nisqually River is already starting to scare people. It has developed a sizable oxbow — a U-shaped curve — on the south side of the I-5 bridge.

The South Sound Military and Communities Partnership reports that a recent U.S. Geologic Survey hydrology study found that “I-5 will be over topped by Nisqually River flooding.” USGS lead scientist Eric Grossman said, “It is not if, but when.”

The science tells us that in as little as 17 years flooding events will become much more frequent in the Nisqually delta, with the oxbow on the river reaching the freeway. This would result in more frequent events like the 1996 Chehalis flood that closed the freeway, but on the Nisqually delta. In fact, Grossman concludes that it might be worse than the Chehalis flood that put I-5 under 9 feet of water.

The Nisqually Tribe has been working to draw attention to this problem for many years. Last year the tribe split the cost of the USGS study with the Washington state Department of Transportation.

The tribe has another reason to care about this problem too. Juvenile chinook salmon need to spend months in a mix of saltwater and freshwater to grow and prepare for life in the open ocean. Only a part of the Nisqually Wildlife Refuge provides that specific habitat, and it is being squeezed as the sea level rises and pushes it towards the I-5 dam. If that habitat continues to shrink, the Nisqually River’s chinook run will perish. That would be an unfathomable loss not only to the tribe, which has spent decades working to restore that run, but also to endangered orca whales, who eat chinook from the Nisqually as they swim through Puget Sound on their way home from the open ocean.

The challenge is to get I-5 up off the valley floor, and to replace and raise the river bridges. One question is, of course, how high to raise it all. Some advocate making it high enough to eliminate or at least reduce the long uphill climb on the west side of the valley, where trucks typically slow way down as they approach Lacey. That would certainly make for more efficient use of the freeway.

David Troutt, the Nisqually Tribe’s natural resources director, says “When I talked with Billy Frank about the issue, probably 10 or so years ago, he said we should build an elevated bridge from the JBLM golf course to Hawks Prairie. It would look amazing ... and probably cost $15 billion.”

That’s the kind of visionary thinking that made Billy Frank Jr. so beloved.

There will be plenty of time to think about how high the freeway is later; right now the more urgent conversation is about the next steps to get it up off the valley floor so that nature can do what nature does with rising waters and growing salmon.

The immediate challenge is to get money in this year’s state transportation budget to start the environmental review and design work that could get us to a construction start in 2027.

The request for initial funding is part of a $204 million county-wide package endorsed by Lacey, Olympia, Tumwater, Yelm and Thurston County. The package includes several other projects, including work on the I-5 interchange with U.S. Highway 101, the interchange at 101 and Black Lake/Cooper Point, and improvements to the Pacific Avenue interchange. Of the $204 million, $7.5 million is needed for Nisqually.

We agree with the South Sound Military and Communities Partnership, which says “the crossing of the Nisqually Delta is the most critically and strategically important stretch of I-5 in the region.”

We urge state legislators to include it, along with the other Thurston County projects, in this year’s biennial transportation budget.

This story was originally published January 31, 2021 at 5:45 AM.