Located directly adjacent to Seattle’s urban core, Lake Union has served as a hub for the industry since settlement began in the early 1900s, where log mills processed the region’s old-growth timber, creating the building materials that dominated local commerce. The Project Team was designing a commercial building on the north side of the Aurora Bridge when the developer learned about the lethal effects of roadway runoff on the region’s salmon. Studies performed on a nearby bridge, consistent with national databases for high-traffic roadways, showed that soil could filter and eliminate the lethal effect. Similar tests on stormwater runoff from the Aurora Bridge proved to be five times greater than the levels measured in the study. The especially toxic effluent had been flowing untreated into Lake Union for almost a century, presumably impacting human health, spawning salmon, and subsequently, the local Orca population, which is headed towards extinction due to a shortage of salmon prey and high levels of toxic stormwater.

The swales step down every two feet of grade, with Corten steel weirs holding water as it filters sediment and contaminants, allowing clear surface water to outfall into the adjoining cell. Phase Two adds staggered concrete walls slowing building runoff flow to promote evaporation. Their geometry echoes that of the log booms and logging industry present at the site. Cut into each concrete wall, bronze spillways create a flat area for bees to drink from during the summer months. The swales come alive with each storm, as water pours over the weirs, mixing the sound of water with the sound of cars overhead. A block downhill, Phase Three features a spillway to settle incoming water before meditatively overflowing. Five low-standing steel walls punctuate the planting, channeling the water. Native shrubs and rushes are consistent within all phases, along with Vine Maples that serve as a deciduous understory canopy, speaking to PNW’s regional forests. Flowering plants were prioritized to support native and non-native pollinator species in the area.