Remove Culverts for WA’s Climate Resiliency

Record-setting rainfall this past week sent Puget Sound’s rivers and streams over their banks, flooding homes in Snohomish County, closing roads and triggering mudslides. The atmospheric river was another blunt reminder of the dangers floodwaters pose to human-made infrastructure, including the culverts that guide waterways underneath the region’s roads.

At least one creek’s surge outside Port Orchard overwhelmed a three-foot-wide metal culvert beneath Sunnyslope Road, washing out the road above it. Repairs will take months, closing the thoroughfare indefinitely.

Culverts, the artificial pipes that squeeze once-meandering streams through a bottleneck of concrete or metal, exact an ecological toll on species like salmon. But they’re also an increasing liability in an era of climate change. Washington’s transportation network must become more resilient to such flooding in a time of diminished snowpack, heavy rainfall and rising sea levels.

Washington lawmakers have invested an unprecedented $3.8 billion to remove culverts in the name of creating salmon habitat and upholding terms of a court-imposed injunction to meet tribal treaty fishing rights. Billions more will be needed to complete the work by 2030 at a time when the Legislature is grappling with skyrocketing costs for all its transportation projects.

An often-overlooked benefit of the Washington State Department of Transportation’s culvert replacement program is the strengthening of its highway network against the more frequent floods that will come with an increasingly chaotic climate. The department is building more bridges — rather than replacing one culvert with a bigger one — more often than the agency anticipated, according to reporting by The Seattle Times’ David Kroman and Mike Reicher. While that has driven up costs, it leaves behind a spacious stream bed more able to accommodate larger flood events and infrastructure built to last 75 years, according to Kim Rydholm, WSDOT’s fish passage delivery manager.

“The nature-based designs used in these projects help ensure they can withstand current and future threats,” she said.

As costly as it is, culvert removal is not some passing infrastructure fad. The obligations of governments at all levels and private landowners won’t go away in 2030. Thousands of miles of culverts have already been replaced since such work began in the 1990s. And as many as 20,000 more barriers will still block streams, even if WSDOT completes its court order.  

WSDOT should continue forging ties with local governments and private landowners to help open bigger stretches of waterway by taking out multiple blockages across jurisdictions. The federal government, by way of the Bipartisan Infrastructure Act, has allocated $1 billion toward removing culverts that can help pick up the tab in Washington. The more comprehensive the project within watersheds, the better return on investment — ultimately, more habitat for salmon, and a return to the pristine conditions when they were far more plentiful.

Removing culverts accomplishes more than habitat restoration. It gives all Washingtonians a more climate-resilient future.  

Source : Seattle Times