After years of planning and discussion, construction is now underway on a new 50-acre public park along Boise’s Greenbelt at Ada County’s Expo Idaho property, marking a major step forward in redeveloping the former Les Bois Park horse racing track.
The project, known as The Park at Expo Idaho, broke ground late last year and is scheduled for completion in 2026. The park is being funded with $32 million in American Rescue Plan Act (ARPA) dollars, allocated to Ada County as part of the federal COVID-19 recovery effort.
Designed by Philadelphia-based firm PORT and built by CM Company, the park represents the first phase of a broader redevelopment of the Expo Idaho site surrounding the Western Idaho Fairgrounds. A second phase — still under contract negotiations — is planned for the western portion of the property and could include a professional soccer stadium through a public-private partnership.
Josh Brown, Ada County’s senior project manager, said the completed park is expected to draw visitors from well beyond the county.
“You could show up on an ideal day there could be a soccer game going on, you could go to a baseball game, you could go play in the park, the kids could go play in the skate park,” Brown said. “There’s nothing like this in the Northwest.”
A defining feature of the project is its emphasis on environmental restoration and ecological design. Rather than reshaping the floodplain near the Boise River, the park’s layout leans into the natural wetlands and topography of the area.
More than three miles of trails will wind through ridges and valleys carved into the landscape, creating meandering streams and low-lying wetlands designed to support wildlife. Native plants — cultivated in 15 nurseries across the Mountain West and Northwest — will populate the park, representing more than $10 million in plant investments.
“We’re not just spraying grass out here,” Brown said. “This is about native species and ecological uplift. We’re returning this space to what it was before we showed up.”
The design allows for natural processes to shape the space over time, including habitats suitable for beavers, birds, and other wildlife, while elevated ridges will offer visitors views of the Boise foothills.
Among the park’s signature features is a 5-acre skate park designed by California Skateparks, the same firm behind the skateboarding venue used during the 2024 Paris Olympics. The skate park will be integrated into the surrounding landscape, making it easily accessible from the Greenbelt for cyclists and pedestrians.
Near the skate park and the Plantation Island bridge, the county is also constructing a food truck park with seating for live music and events, modeled after similar Greenbelt-adjacent spaces in downtown Boise.
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A pavilion designed by Marlon Blackwell Architects will provide shaded seating and year-round restrooms. Brown described the pavilion as both functional and artistic.
“It’s designed so when the sun rises it catches shadows in certain ways,” he said. “As the sun is rising, it’s casting these unique shadows down on the ground and the way the panels are designed it reflects light at different times of the day. It’s an art deco piece with all the functions of a pavilion.”
At the eastern end of the park, visitors will find a large playground built for a wide range of ages, from toddlers to adults. The play area will feature climbing walls, slides, ropes, and varying elevations integrated into the surrounding terrain.
The park will also include what Brown described as “the largest swing set west of the Mississippi,” designed to accommodate adults and inspired by the former rails of the Les Bois race track. A 64-foot zipline will add another element geared toward both children and adults.
“Our design principle was all about the entire family,” Brown said. “If you come out with grandparents and they want to sit and watch music, and if you have a caregiver that wants to hang out with smaller kids and if you have kids that are daring and want to bring their skateboard or bike over to the skate park you’ve got the skatepark, so entire family engagement.”
Once construction is complete, Ada County will still have approximately $7 million in remaining ARPA funds reserved for contingencies. Whether those dollars will be used remains uncertain.
“It’s very difficult to know if we will use those funds,” Ada County spokesperson Elizabeth Duncan said in an email.
When finished, The Park at Expo Idaho is expected to transform a long-underused property into a regional destination that blends recreation, ecology, and community gathering space along one of Boise’s most popular corridors.
Originally reported by Margaret Carmel - BoiseDev Sr. Reporter in Boise Dev.
