San Francisco bringing streams to the surface again

July 2019—Your city is inevitably crisis-crossed with streams you don’t know are there. In the process of development, many of these are forced into underground pipes. The process of bringing them back is called daylighting. There are a lot of advantages: providing habitat, creating gathering areas for urban residents to enjoy nature, and reducing the urban heat-Island effect. It can also restore aquifers as San Francisco discovered.

These efforts to restore aspects of San Francisco’s natural hydrology are also supplying some local water to residents. Although 8,000 people who live and work in the Presidio’s historic buildings get about 80 percent of their supply from a local waterway called Lobos Creek, Stringer says, most San Franciscans have not used local water since before the city infamously dammed Hetch Hetchy, a valley near Yosemite National Park, to supply itself with water from 167 miles away. But in 2017 the PUC began pumping groundwater to augment the public supply from a site in the city’s southwest, an aquifer refilled by green infrastructure projects.