Arboretum Sewer Trestle

The Arboretum Sewer Trestle is a concrete bridge featuring six arched spans of concrete and brick that crosses above Lake Washington Boulevard. The structure connects different areas of the arboretum while carrying a sewer line over the roadway beneath.

The bridge was designed in 1910 to carry a new sewer line across low ground where the arboretum sits today. It gained recognition on the National Register of Historic Places in 1982 and became an official city landmark.

The structure serves visitors today as a notable feature where industrial function blends quietly into the park's natural setting. People often discover that they are walking over an active utility system while enjoying the arboretum's trails.

The bridge is easily accessible on foot as part of the arboretum's regular trail system without special preparation needed. Visitors can explore it as they walk through the park without any detours or additional planning.

The bridge pairs concrete and brick in an unusual multiarch design that shows early twentieth-century construction methods. This combination of materials was an inventive approach at the time for spanning long distances over low ground.