City of Portland, Oregon

Located at the confluence of the Willamette and Columbia rivers, the city of Portland (2.3M inhabitants) receives as much as 380 m³ (100 billion gallons) of stormwater per year.  During very heavy rainstorms, runoff from buildings, streets, and other hard surfaces can fill the city’s old, combined sewers to capacity and cause them to overflow. After more than three decades using green infrastructure as an integral part of its stormwater infrastructure the city of Portland has become one of the pioneering cities in the US on using this approach. With more than 200 green streets, combined with green parking lots, floodwater detention and restoration basins, etc., the city has developed an integrated catchment approach to reduce runoff while enhancing aesthetics, recreation activities and preserving biodiversity. As part of this strategy, land use acquisition has also expanded the city’s green areas to sustainably manage stormwater runoff, stop the spread of invasive plants, restore native vegetation, protect sensitive natural areas, and replace culverts that impede fish passage. Using social and environmental indicators, the effectiveness of all these projects is monitored periodically.