A massive engineering project on Interstate 90 east of Snoqualmie Pass is continuing to show benefits on multiple levels, but while drivers may see improvements to their travel times and conditions, there is an unheard contingent that is also seeing their lives improved.
A series of wildlife underpasses and the wildlife overpass near Hyak are seeing major improvements to wildlife migration patterns, with species from large to small utilizing the structural improvements. Along with the benefits to the wildlife, an additional bonus is that drivers are experiencing much lower incidences of collisions with creatures such as deer and elk during their travels over the pass.
The Topic of wildlife response to the project was the subject of a presentation during Monday night’s Kittitas Field and Stream Club monthly meeting at Hal Holmes Community Center in Ellensburg. On hand were Okanogan-Wenatchee National Forest Wildlife Biologist Patty Garvey-Darda and Washington State Department of Transportation Assistant Regional Administrator for Development Bryan White, who presented an award-winning film that highlighted the ecological benefits to the project and answered questions from the group on the project’s progress.
While the project is still in progress, the focus of Monday’s presentation was the massive numbers of animal crossings at the series of underpasses and a single overpass currently in use. According to their presentation, during 2020 and 2021, over 8,600 large animal crossings were documented throughout the completed Snoqualmie Pass East phases of the project, with a near absence of wildlife-vehicle collisions in the completed phases.
The crossings are not limited to large animals such as deer and elk. At one undercrossing alone at milepost 60.9, creatures ranging from coyotes to marmots were documented crossing, and the location documented a cougar utilizing the passage in 2020.
During the presentation, Garvey-Darda explained that the initial construction of the interstate over the pass disrupted traditional migration patterns of wildlife that traditionally would travel between northern portions of the Cascade Range and southern portions, spanning from North Cascades National Park to Mount Rainier National Park. As the numbers begin to gain traction and biologists get a better understanding of the results of the project, she said clearer pictures are beginning to develop.
“What’s happening with these large wildlife crossing structures is we now have created migration corridors,” she said of the completed phases of the project. “They might have been dispersed in the past, but we now have specific migration corridors.”
Although drivers may not be able to get an accurate scope of the crossings that exist under the freeway, Garvey-Darda said they are impressive in scope. According to development standards, she said they must be a minimum of 120 feet wide, and they must have a minimum of 12 feet of clearance above the average snow load.
“Up close to the pass, that’s 18 feet,” she said of the average snow load that was factored into project development. “As you get to the Keechelus Dam, it’s 16 feet. Those were the minimums, and most structures are much larger than that.”
Although they may not be easy to spot from the roadway, a series of underpasses are concentrated near the singular wildlife overpass, and Garvey-Darda said this was due to the lack of passage opportunities that existed near Keechelus Reservoir, saying a concentration of passage structures on the east end of the lake allowed the wildlife to find their way around the bottleneck at the lake.
“That’s where we had streams, and that’s where we had a huge amount of roadkill,” she said of the location of the overpass and subsequent under crossings. “A lot of habitat is there, so we wanted to concentrate there. There are certain areas of the project where there is a concentration of crossings, and there are other areas where there isn’t, and it’s partly because you need to build things where they are constructable.”
Along with the current structures, a second overcrossing is planned for the top of Easton Hill. White said the planned completion of that structure is sometime over the next five years, and the design will be very similar to the completed structure.
As studies come in that show that creatures ranging from salamanders and western toads to bears and elk are benefiting from the opening of migration corridors, Garvey-Darda said the multiphase project is unique throughout the continent and even the world in that the focus has been to support migration for all sizes of animals and not to focus on large creatures such as deer and elk.
“(The project) is referred to as the crown jewel of the world,” she said of the project’s reputation for wildlife migration success rates. “There is no place that has done what we’ve done at this level.”
Clear skies. Low 27F. Winds NNW at 15 to 25 mph. Higher wind gusts possible..
Clear skies. Low 27F. Winds NNW at 15 to 25 mph. Higher wind gusts possible.
Updated: October 17, 2022 @ 4:01 pm