A new trail that winds through is bringing to focus plants previously hidden and a stream that used to be underground in pipes and culverts.

The paved path completed this winter creates more opportunities for pedestrians, wheelchair users, slow-moving cyclists and families with strollers to explore the arboretum, which features one of the nation’s most diverse plant collections west of the Mississippi River.

The trail and the various plant collections it now gives access to have caught the attention of visitors to Seattle’s largest public garden — and that of the staff who are intimately familiar with the collections.

“People are really experiencing new vistas with this trail, and even as staff, we are noticing you can see things you couldn’t before,” said Ray Larson, curator of living collections at UW Botanic Gardens, which cares for the arboretum’s gardens, trees and plants. “Really special groups of plants were hidden before and now have room to breathe. It’s nice to experience the arboretum in a new way.”

The UW together with Seattle Parks and Recreation and the Arboretum Foundation on Sunday, April 8 with festivities along the path, including live music, free snacks, food trucks, a talk by outdoors writer Craig Romano and a “vine-cutting” ceremony at 1 p.m. The free event is scheduled from noon to 3 p.m. Parking is limited and organizers are encouraging people to carpool or take public transit.

The two-mile loop through the public garden connects a new 1.2-mile section to existing Arboretum Drive, from Foster Island Road south to East Madison Street. A new pedestrian walkway off Lake Washington Boulevard East at Boyer Avenue East allows visitors to easily enter the arboretum from an additional location.

“We hope the Loop Trail allows more people to discover the arboretum’s world-class plant collections, but we’re also excited about creating more access for anyone to watch for wildlife, explore urban wetlands and learn something new about our natural world,” said UW College of the Environment Dean and Mary Laird Wood Professor Lisa Graumlich. “Seattle is so fortunate to have this beautiful place where people can immerse themselves in the outdoors without leaving the heart of the city. It’s a wonderful place to celebrate any time of year.”

The project uncovered a stretch of Arboretum Creek, which before was partially shuttled underground through pipes and culverts. Several new bridges along the path serve as stream overlooks, and arboretum staff have noticed more wildlife along the creek since the project was completed.

The creek flows through a natural wetland that also benefits from the project’s restoration work, including about 30,000 new native plants, and deliberately placed tree logs that encourage pooling and create more habitat for wildlife. Rain gardens and natural filtration berms will filter debris from runoff and help manage flooding during large rainstorms.

“The Loop Trail offers a compelling new urban recreation destination for people from all parts of the city,” said Jane Stonecipher, interim director of the Arboretum Foundation. “But once they arrive and see the peek-a-boo vistas of Azalea Way or sense the wildness of the wetlands, I hope they will discover and cherish the many layers that make the arboretum special.”

Elsewhere along the path, hundreds of plants and trees were transplanted, propagated from existing plants and brought in from nurseries to add to the arboretum’s collections. There are many more varieties of rhododendron, oak, and Chilean and Chinese plants, to name a few.

The trail gives new access to several collections that before were hidden from view. For instance, the arboretum’s nationally recognized oak collection is now more visible, as well as its viburnum collection that has a rich variety of species.

Additionally, the wetland area along Lake Washington Boulevard before had several disjointed footpaths that were fully underwater by late fall. Now that area is reachable with the path, footbridges and new drainage features.

Eight interpretive signs along the trail highlight the plant species, garden areas and arboretum features visible from each spot.

“Years of planning with our UW and foundation partners as well as countless hours of community involvement have helped create this fantastic new trail, which provides year-round, all-weather access within the arboretum,” said Christopher Williams, Seattle Parks and Recreation interim superintendent. “Access for all is one of Seattle Parks and Recreation’s core values that guided us in the development of the trail, and now everyone can enjoy the opportunity of exploring the amazing plant collection at the arboretum.”

Since the construction fences surrounding the new path started coming down last November, arboretum staff say they have seen at least a 50 percent increase in people stopping by the visitor center. They attribute that to how inviting the new trail is to families and first-time visitors — and the fact that more of the arboretum is accessible than ever before.

With its proximity to downtown Seattle, light rail and bus service — and given Seattle’s massive growth — the arboretum is becoming a destination for those seeking nature, said Fred Hoyt, interim director of UW Botanic Gardens.

“A place like this becomes the city’s respite. I think that’s what we’re beginning to see with the visitor numbers going up,” he said. “We have taken this community asset and opened it up to allow a different perspective of the arboretum and a different look at all of the collections we have. To me, that’s the biggest success of this project.”

The arboretum is managed cooperatively between the UW and the City of Seattle, with support from the Arboretum Foundation.

The loop trail project and restoration work were funded by the Washington State Department of Transportation as part of the SR 520 bridge construction. The $7.8 million project is part of the arboretum’s 20-year master plan, which was adopted in 2001 after years of public input. The trail was designed by The Berger Partnership and built by Ohno Construction.

“Building this trail in the arboretum is a major milestone and win for the community,” said Denise Cieri, WSDOT SR 520 program administrator. “This is a major step in improving the bicycle and pedestrian network in the area, which further connects to local and regional trails including the new SR 520 Trail across Lake Washington.”

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For more information, contact:

Arboretum plants, collections: Ray Larson: halcyon@uw.edu or 206-616-1118 and Fred Hoyt: fhoyt@uw.edu or 206-543-3137

Loop trail construction: Garrett Farrell, project manager, Seattle Parks and Recreation: garrett.farrell@seattle.gov or 206-233-7921

Arboretum Foundation: Jane Stonecipher, interim executive director: jstonecipher@arboretumfoundation.org

Restoration work on the 6-acre swamp began more than 15 years ago as part of a UW capstone course taught by , a professor in environmental and forest sciences. The swamp was overrun with invasive plants, including reed canary grass and English ivy, and a stronghold of Himalayan blackberry made most of the area impassable.

After mowing down some of the blackberry thickets, Ewing decided to try a less mechanical approach: Plant young, fast-growing willow trees to cast shade on the sun-loving invasives and eventually kill them.

Those initial plantings took hold, grew tall and served as a starting point for robust restoration work. Now, swamp-loving conifers and other native shrubs thrive in the area that has far fewer invasive plants than a decade ago.

“I think people assume a natural area will just heal itself, but in a city, that just doesn’t happen,” Ewing said. “There’s always going to be some restoration needed in Yesler Swamp. It’s great, because we wanted a project that would have an ongoing need, and to involve students in meeting that need.”

Swamps are wetlands with trees, and conifers such as Sitka spruce and western red cedar would have colonized the Yesler Swamp area. Most of Seattle’s original swamps have been logged, drained or filled, and this swamp is one of the only remaining ones along Lake Washington.

“This swamp provides a habitat type that’s rare,” said Zac Mallon, a recent UW graduate who helped with the restoration work. “It provides habitat for wetland birds, migrating salmon and other fish species and amphibians in the Seattle area.”

About five years ago, the swamp’s Laurelhurst neighbors formed the group and began the boardwalk trail project that protects sensitive habitat and keeps walkers’ feet dry when the lake level rises. The boardwalk trail also makes it easier to do ongoing restoration work.

The group raised more than $400,000 to build the 1,500-foot boardwalk, designed by SB&A Landscape Architects. The UW will now assume responsibility for ongoing maintenance and monitoring restoration work within the swamp.

“It is wonderful that the Friends of Yesler Swamp wanted to take on the trail and boardwalk project,” said Fred Hoyt, interim director of UW Botanic Gardens. “It is providing all-year access for the students to work on projects, learn how to deal with restoration and report to the state agencies. The area is an excellent outdoor laboratory that allows us to work hand in hand with the community on a range of activities.”

Hundreds of students have been involved over the years in work parties and research projects in Yesler Swamp. UW students, local elementary school and high school students have taken their turn at pulling out invasives. A number of UW graduate students also have completed thesis projects using the swamp as a convenient test bed.

“For UW students, this is a place to run experiments, to learn about restoration and to try new things,” said Kat Cerny-Chipman, a UW master’s student in environmental and forest sciences. “It’s a forever project, but since this is a place to learn about restoration, that’s actually OK.”

Henry Yesler’s 1800s-era sawmill used to occupy the land now known as the swamp. After the mill burned down, the UW bought the property in 1927 and it sat for years, accumulating a dense, impassable thicket of invasive plants. Now the land is teeming with native plants, a resident beaver (and dam) and more than 100 bird species sightings.

“Because the swamp was forgotten is why we can have this resource now,” Cerny-Chipman said. “I think the specialness of the swamp is really hard to put into words. I encourage people to get out and see it.”

Yesler Swamp is located on the east side of the UW’s . It is free and open to the public.