Wildlife habitat connectivity - Snoqualmie Pass East Project

2022

Snoqualmie Pass East Project improves wildlife habitat connectivity

At the end of 2022, WSDOT recorded the 20,000th safe wildlife crossing by camera at completed structures within the ongoing Snoqualmie Pass East Project, where WSDOT and partners have built 11 large wildlife crossing structures so far. These crossings included 5,959 elk, 12,068 deer, 2,016 coyote and several crossings by rare species like moose, cougar, American marten, fisher, and American pika.

The Snoqualmie Pass East project is located along a 15-mile stretch of I-90 between Hyak and Easton. This corridor passes through the Okanogan-Wenatchee National Forest and is a critical connectivity zone for Pacific Northwest wildlife populations. Ecological connectivity components of the project include more than 20 large wildlife crossing structures, including two major overpasses, and continuous wildlife fencing throughout most of the project area. In addition to improving ecological connectivity across I-90, the project aims to fulfill multiple objectives, including reducing avalanche and rock fall impacts, replacing failing concrete pavement, and adding lanes to reduce congestion.

In August 2022, a moose was documented using a wildlife underpass within the Snoqualmie Pass East Project area to cross I-90, heading south. This moose was approximately 100 miles from its known core range. A couple weeks later, the first moose ever documented in western Washington was recorded in the Cedar River Watershed, and another couple months later, Mount Rainier National Park recorded its first ever moose visitor. While it can't be known with absolute certainty whether it was the same moose it is extremely likely. Wildlife underpass structures allow thousands of safe wildlife crossings annually and give animals opportunities to naturally expand their range into suitable habitats previously unreachable due to transportation infrastructure. Meanwhile, wildlife-vehicle collisions within the completed areas of the Snoqualmie Pass East Project dropped to a consistently low or non-existent level.

Monitoring teams from Central Washington University documented many small mammals, amphibians and fish utilizing the crossing structures, including western toads breeding in a wetland south of the overcrossing two years in a row, culminating in newly-metamorphosed western toadlets safely crossing I-90 using the same overcrossing. Furthermore, coastal giant salamanders and American pika were documented crossing I-90 at multiple structures, and federally-threatened bull trout were documented using holding pools beneath the Gold Creek Bridge.

The project's final two phases (Phases 3 and 4) will address the remaining portions of the corridor by installing seven additional large wildlife crossing structures, including a second overcrossing, and many small and medium-sized bridges and culverts for water and low-mobility species passage.

2021

Snoqualmie Pass East Project improves wildlife habitat connectivity

The Snoqualmie Pass East (SPE) Project is located along a 15-mile stretch of I-90 between Hyak and Easton. This corridor passes through the Okanogan-Wenatchee National Forest and is a critical connectivity zone for Pacific Northwest wildlife populations. The project aims to fulfill multiple objectives, includingreducing avalanche and rock fall impacts, replacing failing concrete pavement, adding lanes to reduce congestion, and improving ecological connectivity across I-90. The project will enhance ecological connectivity for multiple wildlife species at 14 connectivity emphasis areas. Ecological connectivity components include more than 20 large wildlife crossing structures, including two major overpasses, and continuous wildlife fencing installed throughout most of the project area.

Within the completed portions of the Snoqualmie Pass East Project, WSDOT and partners built 11 large wildlife crossing structures.

WSDOT recorded a minimum of 8,683 wildlife crossings by camera in 2020 and 2021. These included 3,202 elk crossings, 4,382 deer crossings, 764 coyote crossings and several low-density and rare species like cougar, American marten, fisher, and American pika taking advantage of the structures to safely cross I-90.

Monitoring teams from Central Washington University additionally documented many small mammals, amphibians and fish utilizing the crossing structures, including a radiotracked western toad that crossed using the overpass.

The final phases of the project will address the remaining portions of the corridor by installing seven more large wildlife crossing structures and many smaller culverts and bridges for water and low-mobility species passage.