Streets are the interstitial spaces that enable cities: they provide a network for all of the dynamic social, economic, and physical activities that make cities vital human habitat. By design, streets channel and convey stormwater, providing a network along which all the rain that falls on the city can be routed. While streets have traditionally functioned to collect and drain stormwater to water treatment facilities and designated outfalls, streets that capture and infiltrate stormwater back into the urban ecosystem can generate enormous ecological, economic, and public health benefits.
Concrete and asphalt dominate urban landscapes. Typically in urbanized areas, 60% of land or more is impervious surface. Water that falls on roofs, streets, and parking lots cannot soak into the ground, and instead becomes stormwater runoff, collecting pollutants like oil, grease, heavy metals, and bacteria before flowing through gutters and storm drains, and eventually discharging into local water bodies.
Streets present both a barrier to natural hydrology and an enormous opportunity for a better approach to stormwater management. Public rights-of-way are controlled by city agencies, from design to construction to operations to regular maintenance and permitting. Interdepartmental coordination enables more streamlined and holistic projects, ensuring that streets not only collect and infiltrate stormwater, but also realize the potential health, safety, and mobility benefits of urban stormwater street design. Integrated design strategies address water quality and regulatory compliance along with traffic calming, bike and pedestrian access, safety, urban greening and aesthetic improvements, air quality, urban temperature, public health, community development, and equity.
Streets can be changed; the time to act is now.