2024-2025: Wildlife-Vehicle Collision Subcommittee
- cece8202
- May 6, 2024
- 7 min read
Updated: Apr 3
The Wood River Valley community cherishes the beautiful and abundant wildlife of its surrounding mountains and watersheds. The valley itself is a wildlife corridor, yet us humans have settled in it. The human impact on habitats in the Wood River Valley is undeniable, and will persist as long as the cities exist in the valley floor. To mitigate these impacts, coalitions like the Wood River Valley Wildlife Smart Communities, organize people to address the pressure points where human activities negatively impact wildlife.
One area of concern is wildlife-vehicle collisions along State Highway 75. The attached flyer and following drop-down sections are available for you to read more about the big game migration routes across the region, the local resident elk herd, the rate of wildlife-vehicle collisions in Blaine County, the history of mitigating wildlife-vehicle collisions on the highway, current context of highway widening, and the local effort to reduce wildlife-vehicle collisions.
Regional Migration Routes & the Resident Elk Herd
Big game migration Routes in the Smoky-Boise Complex Priority Area
While the local resident elk herd contributes is involved in the majority of wildlife-vehicle collisions (WVC) in Blaine County, the Wood River Valley also channels migratory wildlife. The Smoky-Boise Complex Priority Area contains critical migration routes of pronghorn, mule deer and elk. In Blaine County, these migration routes bisect US-20 south of Bellevue and SH-75 north of Ketchum, as shown in the snapshot to the right.
This snapshot only reflects a portion of IDFG’s mapped migration routes, and does not reflect the resident elk because they do not migrate. This map was created and approved by Idaho Fish & Game.
The Local Resident Herd: Year-round residency in the Wood River Valley
The Wood River Valley is home to many wild animals, including elk that live in the valley year-round and others that migrate in the Smoky-Boise Complex Priority Area (see above).
Human influenced landscapes along the Big Wood River have provided the resident elk herd with high quality forage, access to water and relative safety, allowing them to increase their population and reside in the valley year-round. As such, they have stopped migrating. Idaho Fish & Game estimates that there are currently several hundred resident elk in the Wood River Valley, noting that all elk populations that frequent the valley have steadily increased since the 1970's.
The resident herd is also involved with the majority of wildlife-vehicle collisions in Blaine County, occurring north of Hailey. As the resident elk meander between the river and fodder on the valley floor, they risk their lives and pose a safety hazard for the increasing number of commuters on SH75. See below for details about the locations and rates of wildlife-vehicle collisions in Blaine County.
Rate of Wildlife-Vehicle Collisions (WVC) in Blaine County
The community is aware and concerned that more than 20% of the crashes in the County involve wildlife vehicle collisions (Blaine County Safety Action Plan, 2024). Additionally, the Idaho Transportation Department estimates that the road segment north of Hailey had the 3rd highest official crash rate across the state, from 2018-2022. For an overview of wildlife-vehicle collisions across the State, see Blaine County under District 4 of ITD's WVC Crash Hotspot Dashboard or the ASHTOWARE Safety Tool.
Wildlife-vehicle collision data is collected through:
Blaine County Sheriff's Office, which responds to crashes, and
Idaho Fish & Game, which collects data from a portal where people are able to report road kill and salvage.
In 2023, a coarse-scale analysis of highways across 11 western states, named the “West-Wide Study to Identify Important Highway Locations for Wildlife Crossings,” marked the hotspots in Blaine County as being salient by measures of safety, economics and ecological connectivity. Seven hot spots in Blaine County fell within the top 10th percentile for wildlife-vehicle collisions and the top 50th percentile for ecological connectivity, across the 11 states analyzed in the study. All seven of the Blaine County hot spots identified in the study were located within 1 mile of a protected area– meaning that safe crossing could significantly benefit habitat connectivity.
History of Local WVC Mitigation Measures
In 2013, following the first phase of the current highway expansion projects, the Blaine County Regional Transportation Committee launched a citizen science campaign to collect wildlife vehicle collision data. For background on the activities and success of the 2013 campaign, see:
The article, "ITD to play key role in reducing vehicle-animal collisions," published in 2013 by the Idaho Transportation Department in their series: The Transporter.
The article, "Physics class studies deer, elk collisions with vehicles," published in 2013 by the Idaho Transportation Department in their series: The Transporter.
The 2013 news release, "Night speed-limit changes on Idaho 75 begin next week," by the Idaho Transportation Department.
The Idaho Transportation Department (ITD) responded to local concerns about the high number of crashes involving wildlife-vehicle collisions by:
reducing night-time speeds and light-sensitive warning beacons (responsive to vehicle headlights).
improving the design of Hospital Bridge to allow for wildlife passage beneath it, along the riparian corridor, and
installing additional wildlife warning signage elsewhere on SH-75.
These mitigation measures diverged from the SH-75 roadway design and plans that were approved and built per the 2008 Final Environmental Impact Statement (FEIS).
In addition to the 2008 FEIS, the County and ITD commissioned a supplemental white paper from the Western Transportation Institute at Montana State University, titled "Wildlife-Vehicle Collision and Crossing Mitigation Measures: A Literature Review for Blaine County, Idaho." See page 91 of the report for its nuanced conclusion, plus earlier pages for the variable effectiveness of mitigation measures. A more technical report deliberates the costs, benefits and feasibility of installing an animal detection system (ADS) on SH-75; although none was ever installed. However, modifications to the two bridges along SH-75 were adopted per the report's recommendation.
Highway Widening: Current SH-75 Infrastructure Projects
Three major highway redesign and reconstruction projects are underway, all under the purview of the 2008 Final Environmental Impact Statement (FEIS). They include:
ITD's project, SH-75 Bellevue to Broadway;
ITD's project, Idaho 75: Elkhorn Road to River Street; and
The designs for the SH-75 Bellevue to Broadway project have been presented, and are publicly available for reference on the ITD project website. The designs include:
highway widening for passing lanes, left-turn lanes, shoulders/clear zones, and sight distance;
improving drainage;
building pedestrian and bicycle underpasses at the Deer Creek Road, Ohio Gulch/Starweather Drive and Broadway Run intersections;
building bus pullouts at the Deer Creek Road, Ohio Gulch/Starweather Drive and Broadway Run intersections; and
building a Park n' Ride lot near the Ohio Gulch intersection; and
signalized traffic control at Gannett Road.
The project is majorly funded by state funding, via the Transportation Expansion and Congestion Mitigation (TECM). Mountain Rides was awarded a federal RAISE Grant for the bicycle, pedestrian and transit facilities included in the project.
ITD plans to publish an environmental re-evaluation for the SH-75 Bellevue to Broadway in 2025. The report's publish date has been pushed back numerous times, over the past two years. The report is expected to re-evaluate the environmental impacts of the project on Land Use, Parks and Recreation, Economic Conditions, Farmlands, Soils, Agriculture, and Geology, Vegetation, Wildlife, Fisheries (Aquatic Wildlife), Social Conditions, Waters, Wetlands, Air Quality, Visual Resources, Noise, Cultural Resources and Section 4(f) Resources.
Exploring WVC Mitigation Measures
In re-evaluating the environmental impacts on big game crossing the highway, ITD is participating in the "Assessment of Wildlife-Vehicle Collision Mitigation Measures in Blaine County," funded by generous supporters of the Wood River Land Trust. On the SH-75 Bellevue to Broadway project website, ITD has published their consideration of the following mitigation measures:
Increasing the extent of nighttime speed limit reductions.
Installing roadway lighting in frequently crossed areas. Lighting would comply with Dark Sky ordinance requirements.
Working with the Idaho Department of Fish and Game to consider other feasible options.
ITD also evaluated wildlife overpasses, which are not considered to be feasible for a variety of reasons, including:
the high number of driveway curb cuts, interrupting fencing;
the limited funding for crossing structures; and
more critical crossing needs for species in other parts of the State.
If you're interested in learning more about measures that are known to mitigate wildlife-vehicle collisions, this 2021 literature review offers a substantive overview of different types of measures and discusses what is known about their effectiveness.
2024-2025: Wildlife-Vehicle Collision Subcommittee
As part of the Wildlife-Vehicle Collision Subcommittee of the Blaine County Regional Transportation Committee, the Wood River Land Trust has commissioned a road ecology team from the Center for Large Landscape Conservation (CLLC) to:
Conduct a spatial analysis and prioritize highway sections, based on a crash, migration route and habitat suitability data
Develop recommendations for how to reduce wildlife-vehicle collisions on the priority road segments
Support community engagement around the study’s methodology and recommendations; then,
Compile, deliver, and present their recommendations and final written report to local decisions makers and regional transportation planners
There are many possible ways to reduce wildlife-vehicle collisions. However, factors like the geography of the constrained corridor, the location of driveway curb cuts on the highway, plus the installation and maintenance costs of different measures render some more feasible than others.
Blaine County Commissioner Angenie McCleary states that, “The County is committed to improving roadway safety and living in harmony with our local wildlife. A closer look at treatments that are known to reduce wildlife-vehicle collisions, including how well they’ll perform on Highway 75, will be useful to pursuing a solution.”
In addition to fielding feedback from the subcommittee and public, partner organizations Blaine County, Idaho Fish & Game, Idaho Transportation Department, and Idaho Conservation League will help steer the scope and completion of the assessment by the Center for Large Landscape Conservation. The assessment is due to begin in May 2025 and commence a year later.
Meeting 1: March 14, 2024
Presentation slides from Idaho Fish & Game
Meeting 2: June 17, 2024
Press release: November 19, 2024
December 9, 2024
Request for Proposals
