Mercer Slough Nature Park

Updated 8/4/2021

Update: Light Rail Construction has closed the South Bellevue Park and Ride. It is not possible to access the park from there. This hike is not recommended at this time.

Before 1917, the site of Mercer Sough Nature Park was a shallow bay of Lake Washington. Steamboats carried passengers up Mercer Slough to the booming lumber town of Wilburton. In 1917 the Seattle Ship Canal and locks were constructed, which lowered the lake by ten feet and turned Mercer Slough into a marshy flat. Farmers found the wet ground idea for growing flowers, vegetables, and berries, and soon the area became a patchwork of farms and berry fields. The prosperous owners of one such farm, the Winters Family, constructed a large house near to their farm and greenhouses in 1929. This ornate house, built in the Spanish Eclectic style, still stands and may be visited today. In1956 the City of Bellevue bought up many of the farms and created the current 320 acre park.

Today the park makes a great destination for hikers. Several miles of trails ramble through the wetlands, many of them built on boardwalks. Bus access is very easy from Seattle.

Mercer Slough

Getting There & Back

Unfortunately, the closure of the South Bellevue Park and Ride due to light rail construction has made accessing the park difficult.

Use TOTAGO to get round-trip transit directions, plus offline trail maps if you download the app:

Mercer Slough Nature Park on Totago

The Hike

There is a trailhead at the south side of the park-and-ride lot. Follow the well-signed trail into the expansive wetlands of Mercer Sough. In 0.2 miles, the trail reaches a junction with the Heritage Loop Trail. Go left to visit the farmers market (open seasonally) and u-pick blueberry farm. In 0.4 miles you arrive at the historic Winters House. You are welcome to go inside to view its beautiful interior, and park staff can give you a short tour of the house. This is also a good place to pick up maps and brochures on Bellevue parks and trails. The "Nature Trail Guide" booklet in particular is good to have.

The Heritage Loop Trail heads back into the interior of the park beyond the Winters House, circling north around the berry farm then along the side of Mercer Slough. You then arrive at a pedestrian bridge crossing the slough. Cross the bridge to access a second trail loop, the 0.6 mile "Bellefields Loop". This trail features more wetlands and marshes, and a bit of elevation gain at the east side of the park where it climbs a hillside below 118th Ave. There are some beautiful cedar trees here.

The walk from South Bellevue Park and Ride around the two trail loops is about 2.5 miles. If you want more walking, you can follow all or part of the 4 mile Periphery Loop that circles the park. This is a paved trail close to roads and not particularly quiet or natural for the most part. There are a couple of attractions you can reach by hiking the Periphery Loop. Located on 118th Ave SE just north of the Bellefields Loop trailhead, the Environmental Education Center has a visitor center and a short nature trail. At the north end of the loop is the Mercer Slough Fish Ladder which allows salmon and trout to reach Kelsey Creek, the main source of water for the Mercer Slough. On the south end of the loop is a boat launch for canoes, a popular way to tour Mercer Slough.

Another option is to hike the I-90 Trail, which crosses Mercer Slough Nature Park on its south side, to Mercer Island and Luther Burbank Park.

Winters House