The Tolt pipeline provides water to the City of Seattle and runs from the Tolt Reservoir in the Cascades to the Lake Forest Park Reservoir. The pipeline passes though Seattle’s northern Eastside suburbs, and the pipeline’s 100-foot-wide right-of-way has been converted in part to a non-paved, multi-use trail for equestrians, dog walkers, mountain bikers, joggers, and hikers. The trail runs 12 miles from Duvall to Bothell.
The western terminus is located along 104th Avenue NE near Blyth Park in Bothell, and the eastern terminus is along NE 133rd Street in Duvall. Other trailhead access points are in Woodinville along 124th Ave NE, 148th Ave NE, and Avondale Road NE at Bear Creek Road NE (from west to east). Consider parking cars at different entry points if you desire a longer one-way trek.
The trail runs in an east-west direction along most of its length, with few bends or turns. It has a gravel surface, crosses numerous local roads, and climbs several hills along its course. It has sections of variable difficulty, ranging from flat in the Sammamish River valley to the brief but Mailbox-esque incline of Hollywood Hill (nicknamed “cardiac hill”) in Woodinville.
At Woodinville the trail descends into the Sammamish River valley, and it is necessary to follow NE 145th Street to cross the Sammamish River. There are various bridge crossings where the Tolt pipeline makes a brief appearance alongside the trail. There are junctions with other small local trails such as Brooktrails Trail 9, which intersects the Tolt 0.9 miles west of Avondale Road.
The route is sun-exposed through most of its length. This is an excellent “weedflower” hike. Marvel at the invasive and noxious plant species that line the route, including thistles, buttercup, cow parsnip, foxglove, Himalayan blackberry, salmonberry, fireweed, and oxeye daisy. Horsetail, American reeds, and ferns are abundant. When there is a canopy, it is formed by bigleaf maple, Douglas fir, Western red cedar, and alder. There is a mix of wildlife and suburb-acclimatized creatures, with deer and rabbit sightings fairly common; bobcats and coyotes are reported on occasion.