Late Summer in Washington Park: The Arboretum You Can Only Walk Right Now

The path to Foster Island is dry this week. In April it was not. By late October, once the fall rains settle in, parts of it will disappear again under an inch or two of Union Bay. If you live within a few blocks of the Graham Visitors Center, the calendar window you have to walk the full Arboretum Waterfront Trail without wet socks is roughly the one you are standing in.

That is the small, unglamorous fact most guides to the Washington Park Arboretum leave out. It is also the reason this particular August is worth paying attention to.

Three separate capital projects are now underway or funded inside the 230 acres jointly managed by Seattle Parks and Recreation and the University of Washington Botanic Gardens. Each one changes a stretch of the park that residents already walk. Taken together, they mean the Arboretum you loop this month is not quite the Arboretum you will loop in 2028. The point of this post is to map that gap while it is still fresh.

The boardwalk window, and why it closes

The Arboretum Waterfront Trail runs roughly 1.2 miles from the north end of the park, under the SR 520 bridge, across Foster Island and Marsh Island, and out to East Montlake Park. Much of it is a floating boardwalk stitched between wetland tussocks.

The reason the trail is often unwalkable has nothing to do with maintenance. The Army Corps of Engineers raises the level of Lake Washington in spring and holds it high through summer. Portions of the floating boardwalk and on-grade paths sit only a hair above the waterline, so heavy spring rain plus a raised lake means submerged sections. Tripadvisor reviewers describe muddy stretches and boardwalks with visitor shoes going under after heavy rain. Late summer through early fall is the reliable dry window.

The trail along the shoreline of Foster Island connecting to Marsh Island and the Montlake Lid is one of the Arboretum's most spectacular and popular features, and it is well overdue for a makeover.

That is the Arboretum Foundation's own framing, published after Seattle Parks and Recreation superintendent AP Diaz announced at the Foundation's June 18, 2025 annual meeting that the restoration project had finally been greenlit. Designs for rebuilding portions of the floating boardwalk have been sitting in drawers since 2018.

Three projects, one map

Here is what is actually funded, and what it means for the routes you already walk.

Three funded projects on one park is unusual. Each targets a different failure mode of the current experience. The Waterfront Trail addresses seasonal flooding. Pacific Pathway addresses accessibility to a corner of Pacific Connections that most walkers skip because the approach is steep and unmarked. The Ishigaki Wall addresses the ADA-inaccessibility of the Japanese Garden's entry sequence.

The loop most neighbors have not quite put together

If you walk the Arboretum three times a week, you probably have a default route: north end, Azalea Way, back to the car. This is the loop worth doing while all three projects are still visible as before-states rather than construction fences.

1. Start at the Graham Visitors Center on Arboretum Drive E. Open Wednesday through Sunday, 10:00 a.m. to 4:00 p.m., with the gift shop closing fifteen minutes earlier on each end. Pick up the numbered-post trail guide for the Waterfront Trail here.
2. Head south along Azalea Way to Crabapple Meadow, the sloped lawn just south of the Visitors Center where the Seattle Chamber Music Society's Concert Truck performed on July 2, 2026 as part of the Arboretum's 90th birthday programming. In August the meadow is quiet, which is the point.
3. Continue into the Pacific Connections Garden. The Lookout Gazebo sits above the future Pacific Pathway alignment. Walk it before the construction sequencing changes the sightlines.
4. Cut over to Rhododendron Glen and the Joseph A. Witt Winter Garden. Both are underused in August because neither is peaking, which is exactly why the paths are empty.
5. Come back north to the Woodland Garden, then out to the Shoreline and Foster Island section. Foster Island contains some of the oldest plantings in the Arboretum, with specimens dating from the 1930s and 1940s.
6. Cross the boardwalk to Marsh Island and out toward East Montlake Park. This is the stretch that will be under construction, staged, and rerouted in coming seasons. Look for cattails, water lilies, red-winged blackbirds, and marsh wrens. Yes, also two invasives worth learning to spot: purple loosestrife and yellow flag iris.
7. Return the way you came, or exit north to the Montlake lid.

The full loop with the Waterfront Trail spur runs a little over three miles on the AllTrails measure, roughly an hour if you are not stopping.

Small logistics locals still get wrong

The Japanese Garden opens at noon on the first Thursday of each month. For the rest of 2026 that means August 6, September 3, October 1, and November 3. If you have been showing up at 10 a.m. on a first Thursday and finding the gate closed, that is why. The garden is otherwise open Tuesday through Sunday, with adult admission at $10 and free entry for children under six, per the Garden's posted schedule.

Parking on the west side of the Waterfront Trail is a trap. East Shelby Street and East Hamlin Street require residential permits Monday through Saturday. The free option is limited spots along East Park Drive, or the Foster Island parking lot inside the Arboretum. On a Saturday in late summer, plan for the Arboretum lots to fill by mid-morning.

The Cloney-Harris Nursery and Pat Calvert Greenhouse next to the Visitors Center are open April through October. August is your last easy month to buy volunteer-grown perennials before the greenhouse winds down for the annual fall sale. Purchases benefit Arboretum operations directly, which is the sort of civic detail worth knowing when you are choosing between a nursery run there and a run to a chain garden center.

Drones are not permitted anywhere in a City of Seattle park, which includes the Japanese Garden and the Arboretum by extension. If you have a visiting relative with a new Mavic, redirect them to Magnuson.

Why this month, specifically

The overlap of the dry-boardwalk window, three visible pre-construction states, and the Arboretum's 90th birthday programming will not repeat. By next August at least one of the three projects will be fenced and staged. By 2028 the Waterfront Trail alignment itself will be different. The version of the park you already know is the version this month preserves.

If you are the kind of resident who has walked Azalea Way a hundred times and never gone west of Lake Washington Boulevard into Pacific Connections, or who has treated the Foster Island boardwalk as a nice-idea-in-theory because it always seems to be underwater when you check, this is the month to fix that.

If you are considering a move within the neighborhood, or thinking about how the Arboretum edge shapes value for the homes closest to it, James Campbell knows the streets around the park and how the coming changes to its edges will read to future buyers. Let's Connect.