The Bay Area’s Rising Groundwater a Toxic Time Bomb

Image: Miro Korenha

by Natasha Lasky, ODP Staff Writer

A lesser-known facet of climate change could threaten California’s San Francisco Bay Brea: rising groundwater. As Bay Area sea level rises, so does groundwater which comes with a host of externalities.  It seeps through basement cracks, chronically backs up toilets, corrodes pipes, and worst of all: resurfaces toxic substances that collect underground.  These substances could manifest as soon as 10 to 15 years, especially in low-lying communities like Oakland. 

The Bay Area is home to numerous industrial sites, past and present, such as lumber yards, canneries, rail depots, and foundries that spilled numerous toxins into the ground, especially because environmental regulations didn’t prevent this practice until the 1960s. Kristina Hill, an associate professor at UC Berkeley’s College of Environmental Design, told KQED last year, “Everything human beings use, they spill.”

Why This Matters: The toxins that could rise to the surface as a result of groundwater swell have been building up in the ground for over 150 years. In many Bay Area communities, groundwater is quite close to the surface (especially so in low-lying BIPOC communities). There’s a danger that groundwater could flow unnoticed into contaminants no longer monitored because they are considered contained, posing a serious risk to human health. 

The Dirty Details: Underground storage tanks have also spilled benzene and toluene into the ground at sites that are currently considered contained, but could be at risk once groundwater levels rise.

Contamination by these toxic substances could go unnoticed since these “contained” toxic sites are not closely monitored. Contaminated groundwater could leak into a basement or crawlspace, or even a broken sewage line, and then vaporize making it possible for to inhale it. 

Alec Naugle, head of the toxics cleanup division for the San Francisco Bay Regional Water Quality Control Board, told NPR: “It’s possible that you have contamination in that water and you might not see it or smell it. You might not know.” These chemicals could cause cancer, or have short-term effects researchers can’t anticipate.


Environmental Injustice:
The neighborhoods most at risk of groundwater rising have large Black and Latino populations, who already suffer the most at the hands of climate change, especially in Oakland. These residents have high rates of asthma — children there are over twice as likely to have asthma than their neighbors across Alameda County. 


Mitigating the Risk:
Silverstrum Climate Associates plan to map groundwater depths and search for contamination in four Bay Area counties after which they’ll identify the most vulnerable and urgent locations. 

The California Department of Toxic Substances Control wants to work with the U.S. Geological Survey to overlay maps that show groundwater swell onto maps of contaminated sites, to alert site managers. 

While these larger-scale projects get off the ground, the city of Oakland can also install a monitoring well to keep track of groundwater levels nearby, especially if they are near industrial sites like dry cleaners, gas, stations, or factories that may leak toxins into the ground. 

Local governments can also enforce standards that address groundwater rise when new buildings are planned or when toxic sites are cleaned up. 

Though this issue presents many problems for the Bay Area, addressing the problem may help give jobs to the Oakland community. Marquita Price, an Oakland native and urban planner, told NPR:  “I don’t want just some outside consultants and companies to come in and carry out the plan. Our unemployment is crazy out here. So this could definitely be a low-entry job that can provide to the community.”

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