Ambitious Wildlife Overcrossing Completed in Washington State

To protect native species and minimize animal-car collisions, a massive wildlife bridge has been built in Washington State.

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by Washington State Department of T
This artist's rendering depicts the completed overcrossing.

Animal migrations across the country are interrupted by highways constructed for humans’ convenience. Because we’ve impeded other species’ journeys, conservation nonprofits and transportation organizations are increasingly constructing “wildlife bridges,” from underground crab crossings to tortoise tunnels, to help animals get where they’re going without being affected by vehicular traffic. The U.S. Department of Transportation’s Federal Highway Administration estimates that 1 to 2 million wildlife-vehicle collisions occur each year, so wildlife infrastructure protects the safety of animals and humans alike, while reducing the financial toll of accidents, enabling animal migration, and reconnecting ruptured habitats.

One such crossing, the Keechelus Lake Wildlife Overcrossing, is near completion in the Pacific Northwest, above a six-lane section of I-90 near Snoqualmie Pass, Washington. This overcrossing is Washington’s first wildlife crossing over an interstate or highway, and the largest wildlife bridge in North America. The 66-foot-wide dirt overpass spans two concrete archways through which vehicles traverse. This bridge allows elk, bears, mountain lions, and other large mammals to cross safely between the north and south Cascades. The bridge is lined with 8-foot walls on either side to direct animals and block noise, and the Washington State Department of Transportation (WSDOT) will plant native flora across the bridge to attract smaller species, such as gophers and salamanders.

WSDOT has worked with multiple agencies, cities, counties, and community groups to develop a long-term vision for improving a 15-mile stretch of the I-90 corridor, and this overcrossing is one of several wildlife bridges, underpasses, and culverts that will be built as part of that plan.