Touring San Francisco’s Historic Sewer System
Click to enlarge visualization of the former San Francisco watershed, with street map and topography. Source: Oakland Museum.
The Mission is more than just a meeting point for different cultures: it’s also a meeting point for different waters.
Hundreds of years ago, two water sources converged along what is now Folsom Street. During rainy season, fresh water flowed east down from Twin Peaks, aligning roughly with today’s 14th and 18th Streets. Those streams met at what was once a salty tidal estuary, and is today home to warehouses and lofts. That estuary waxed and waned with the tides, filling with bay water at times deep enough to float a boat, and then draining to be little more than a sticky mudflat.
Settlers saw an advantage to the watershed’s layout: cows and people drank the freshwater, and deposited their waste in the daily flush of the estuary.
Though it was unsanitary and untenable for a growing population’s needs, the echoes of San Francisco earliest sanitation system can still be found in today’s sewers.
“In order to understand the sewers of San Francisco, you have to be a historian,” said Greg Braswell, an expert on San Fransico’s sanitation facilities, during a recent sewer tour called Fathoming.
The workshop and bike tour were organized by Workspace artist Miles Epstein, whose interest was piqued a year ago when the facility was flooded during heavy rains. Epstein, local water historian (and Thinkwalks tour guru) Joel Pomerantz, artist and geologist Judy West, and Braswell combined their unique knowledge to illustrate some of the more interesting parts of the current and historical system.
