The biggest wildlife crossing you've never heard of

 

Nestled in the Cascade Mountains of central Washington, winding along a 15-mile stretch of interstate is the largest wildlife connectivity project you've never heard of. Deer, elk, mountain goats, bobcats, black bears, foxes, mink, otters, cougars and wild turkeys roam the region’s old growth forests, mountain meadows, streams and glacier-covered peaks. But all too often, they end up dead on the road, trying to cross I-90, the longest east-west road in Washington state.

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An artist's rendition of the Price Creek wildlife overcrossing will look like. Construction should be complete by 2018. Photo courtesy of Washington Department of Transportation.

The I-90 Snoqualmie Pass East Project, now under construction, aims to make that stretch of highway less hazardous for humans and for wildlife. The enormous and expensive facelift includes a makeover of some scary-sharp curves, expansion from four lanes to six, new road surfaces and rock slope stabilization.

The project also includes massive engineering feats meant to help wild animals of all types safely cross the enlarged highway, which carries 27,000 vehicles per day. When completed, there will be around 32 medium- to large-sized undercrossings in up to 18 locations, plus over 100 small culverts to carry surface water along with amphibians and reptiles, and two massive bridges, or “overcrossings”.  “We needed ecological connectivity to prevent the genetic isolation of species,” says Forest Service biologist Patty Garvey-Darda, the driving force behind the project. “The goal was to connect all habitats, all species and all hydrologic features.”

Phase 1, the first five miles of the project, is nearly finished, complete with the first major wildlife underpass at Gold Creek. Phase 2 should begin in 2015, and will include the project’s crown jewel at Price/Noble Creek, one of the most important “Connectivity Emphasis Areas” in the pass: The larger of the two wildlife bridges, an 800-foot long animals-only overpass, strong enough to support a growing ecosystem – trees and all.


Designing that bridge has been a major challenge. “They’re asking engineers to do things that they don’t know how to do,” said Paul James, biologist and collaborator on the project. James is part of a team of scientists at Central Washington University, which is a key partner in the wildlife crossing project along with the Washington State Department of Transportation and the U.S. Forest Service. CWU is helping WSDOT to design underpasses and overpasses that blend with their surroundings.  “We’re vegetating the overpasses and underpasses, trying to mimic the natural habitat,” Garvey-Darda said. “We’re basically trying to get the whole ecosystem in there.” It’s an approach, she says, that has yet to be applied on such a large scale anywhere else in the world.

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The Gold Creek wildlife crossing underpass was finished in October 2013. The crossing is to the left. Photo courtesy of Washington Department of Transportation.

James’ team, focusing on crossings for fish and aquatic life, is also asking unprecedented things of the engineers, accustomed to simply creating underpasses and culverts for flowing water. “Streams are (made of) rocks and trees and logs,” he said, and he specifies that the aquatic crossings mimic that. “And they’re scratching their heads saying, aaaah, we take logs out, we don’t put logs in streams.”

This unique approach is possible thanks to a multi-year, ecosystem-scale ecological study underway since 2008. The university has been conducting baseline research at Snoqualmie Pass on the behavior and biology of more than 200 species. Dramatic changes in elevation and rainfall mean that the 15 mile length of the project encompasses a vast array of species and habitats, a transitional “ecotone” between the state’s dry interior and wet coastal zones.

Another unique feature of the study, says CWU biologist Kristen Ernest, is the large number of “low-mobility” species included in its scope – like pikas, deer mice, red-backed voles, shrews, shrew-moles and Pacific jumping mice. “It’s not normal that other projects like this do this work with smaller critters,” she said. “But it’s important if you’re looking at the region’s whole ecology” and want to design crossings that reflect all kinds of habitats. Not even snails and salamanders escape the team’s careful connectivity research.

So far the project has cost $525 million, completely funded through a voter-approved gas tax. The nonprofit Cascade Conservation Partnership raised $3 million to acquire about 40,000 acres of privately-owned wildlife habitat in the project zone and donate it to the Forest Service. Now it’s helping to raise awareness and secure new sources of financial support for the next phases of the project, including the massive Price/Noble Creek overcrossing, expected to be completed in 2021. WSDOT’s interdisciplinary approach to the crossings project is being used as a model by others – in states like Montana and Colorado, and as far away as western Europe – who face the same problem: how to integrate complex goals like habitat connectivity, wildlife crossing and roadway safety into a single project.  

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Biologists and students weigh small mammals during the baseline biological study at Snoqualmie Pass. Pictured left to right: Patty Garvey-Darda, Craig Fergus, Amanda Tompkins, Kyle Evans, Bryant Sawada, Kris Ernest. Photo courtesy of Rich Villacres, CWU.

One of the project’s smallest but perhaps most important engineering feats is on display at the CWU Museum of Culture and Environment: a child-sized exhibit of the wildlife over- and under-crossings. It’s complete with mock habitats, photos and videos from WSDOT wildlife cameras, engineering equipment, and perhaps the most popular display in the exhibit: animal scat. On its opening night earlier this month, the interactive exhibit drew more than 300 visitors, mostly children. They followed trails of painted paw and hoof prints of all sizes above and below the “interstate,” pretending to be animals crossing the road.

“The children just fall in love with this piece,” said Museum director Mark Auslander. “It’s a trail of scientific discovery...Exploring the environment should be something joyous.”

Auslander expects more than 1,000 visitors before the exhibit closes – perhaps with some future road ecologists among them.

Christi Turner is an editorial intern at High Country News. She Tweets @christi_mada.