Arboretum Sewer Trestle, Concrete bridge in Washington Park Arboretum, United States

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.

A 1912 letter to Seattle's City Engineering Department called the bridge "a piece of ornamental bridge architecture" and "a very much greater thing than the sewer itself." The name Arboretum Aqueduct reflects its second role carrying water, and the alternate name Wilcox Footbridge honours a local figure. Walkers cross it on arboretum paths above Lake Washington Boulevard.

The trestle crosses above Lake Washington Boulevard in the Washington Park Arboretum, so walkers on the boulevard pass directly beneath its arches. The structure also carries a footbridge deck, letting arboretum visitors cross over the roadway on foot. Approach it from the park's paths rather than by car, since the span sits over the road itself.

A 1912 letter to Seattle's City Engineering Department argued the bridge "is not an 'apurtenance of the sewer'" but ornamental architecture "a very much greater thing than the sewer itself." The structure also carries the name Wilcox Footbridge, and on April 16, 2008, a charter bus carrying Garfield High School's girls softball team struck it, shearing off the bus roof and injuring passengers.