Bay Space storms ship sewage into streets, creeks, San Francisco Bay and ocean

A vehicle drives through a flooded area near the Martinez Refinery in Martinez, California on Friday, January 13, 2023. On Jan. 4, the Martinez Refinery Company reported that more than six million gallons of storm water and sewage were dumped into the Carquinez Strait estuary to prevent damage to the refinery. The refinery is one of dozens of minor incidents caused by open manhole covers, ruptured pipes and overloaded sewage treatment plants dumping millions of gallons of wastewater into the San Francisco Bay area. (Jose Carlos Fajardo/Bay Area News Group)

January’s storms offer a disturbing glimpse into one of the Bay Area’s dirtiest environmental mysteries: torrential rains are overloading our region’s vast sanitation system, flushing wastewater where it doesn’t belong.

In just two weeks, downpours across the region triggered the release of millions of gallons of raw sewage mixed with rainwater, according to an analysis by Bay Area News Group, sending contaminated water into dozens of rivers, streams and eventually the ocean and San Francisco Bay 88 reports to the state emergency services.

“Flooded bodies of water contain pathogens,” warned Eileen White, chief executive of the San Francisco Bay Regional Water Quality Control Board. “If you come into contact with floodwaters, you should wash your hands thoroughly with soap and water to ensure you don’t expose yourself to the hazard.”

When wastewater enters homes and businesses, costly remediation and decontamination measures are required to make them safe again. Spills can also have dangerous environmental consequences as human waste, medicines, shampoos and other harmful products are flushed down drains and toilets.

In one incident, the Martinez Refinery Company reported that it discharged more than six million gallons of storm and sewage water into the mouth of the Carquinez Strait, which empties into the San Francisco Bay, on Jan. 4, according to state records. The discharge of partially treated “process water” and stormwater was necessary to prevent damage to the refinery, the company said.

Dozens of other minor incidents were caused by open manhole covers, busted pipes and overloaded treatment plants, from Corte Madera to Woodside and Half Moon Bay to Pleasanton.

State records show that between Dec. 31 and Jan. 3, a total of more than 14 million gallons of wastewater was discharged in the San Francisco Bay area, enough to fill 21 Olympic-size swimming pools, White said. The Jan. 4 storm triggered the release of an additional 8 million gallons, or 12 Olympic-size swimming pools.

More recent publications are still counted. Experts believe that the total volume is likely to be much larger than currently estimated, as the chaotic circumstances of these emergency flooding situations make it nearly impossible to accurately assess the true extent and impact of the sewage pollution.

Like bridges or skyscrapers that are designed to support specific loads, stormwater management systems are designed for weather conditions — and cannot handle the intensity of storms that may only occur once every decade or two.

In dry times, household and business waste is immediately disposed of in sewage treatment plants, where it is never seen, smelled, or considered again.

But two weeks of near-continuous storms have strained the system as torrential rains and flooding invade sewer pipes.

“We saw 13 times our average wastewater flows,” said Andrea Pook of the East Bay Municipal Utilities District.

According to the reports, most of the releases were caused by rainwater flowing back into the streets and up through drains or manhole covers opened by the overwhelming amount of high-pressure streams.

In Redwood City, a spillway discharged polluted water into Borel Creek at a rate of 150 gallons per minute. In San Mateo, 100 to 150 gallons per minute flowed into a storm drain that empties into Polhemus Creek. About 50 gallons per minute were dumped into Sonoma Creek. In Oakland, 25,000 gallons overflowed into Lake Merritt from three manholes.

When a sewage lift station in Daly City overflowed due to rainwater, 35,950 gallons of waste was dumped into the Pacific Ocean. The rupture of a main treatment line at Moss Beach also resulted in a spill into the sea. In Pacifica, an overflowing pumping station resulted in 20,000 gallons being pumped out at Linda Mar Beach. About 34,000 gallons were released in the Belle Haven neighborhood of Menlo Park when a West Bay Sanitary treatment plant couldn’t keep up with the flow.

According to a Jan. 11 report, the West County Sewage Plant in Richmond pumped sewage directly into the San Francisco Bay. “It is not known how long the release will take,” it said.

Three outflows into San Leandro Creek, Barnhill Marina, and an estuary at the foot of Alice Street in Oakland emanated from the East Bay Municipal Utility District’s “overflow” structures, which are designed to discharge high-flow water.

Further south, a sewage treatment plant was flooded on Friday when the Salinas River overflowed the banks of a levee. Infiltration ponds in the city of Templeton were also flooded, dumping 300,000 gallons into the river.

Cal Fire Caption Curtis Rhodes walks past a home flooded by the Salinas River on Chualar Road near Chualar, California on Thursday, January 12, 2023. Like many overloaded sewage treatment plants, a Monterey County sewage treatment plant was flooded on Friday when the Salinas River rushed over the banks of a levee. (Doug Duran/Bay Area News Group)

Mother Nature creates additional chaos. In Oakland, a tree fell on the sewer line, dumping 5,100 gallons of sewage into Sausal Creek. At Crockett, a mound eroded and collapsed, rupturing a pipe and releasing 2,700 gallons. When debris blocked a sewer line, about 10,000 gallons spilled into a drain leading to Lake Temescal in Oakland.

Records show that a single day—December 31, New Year’s Eve—with 51 layoffs in various Bay Area cities was responsible for the largest number of reports to the California Governor’s Office of Emergency Services.

That morning alone there were 15 sewage discharges in 12 cities: Hillsborough, Woodside, San Bruno, Daly City, Pacifica, Burlingame, Half Moon Bay, San Lorenzo, Richmond, Piedmont, Oakland and Daly City. As of midnight, there were another 36 discharges in 25 cities: Alameda, Oakland, San Mateo, Richmond, Pacifica, Martinez, El Granada, Montara, Pittsburg, Corte Madera, San Francisco, Antioch, Redwood City, Dublin, San Leandro, Albany, Berkeley , Woodside, Vallejo, Menlo Park, Benicia, Sausalito, Pleasanton, Foster City and Hayward.

The problem isn’t new, said Sejal Choksi-Chugh, executive director of San Francisco Baykeeper, a nonprofit focused on San Francisco Bay health. But the constant rain has exacerbated the problem.

“Over the years, and usually every time it rains, we see sewage spilling on the streets and sewage overflowing,” she said. “But the successive major storm events are leading to a continuous discharge. That’s the new thing.”

Experts say that as the population continues to grow, the demands on our sewage systems have increased. Now, more construction means more asphalt and cement, so most of the precipitation ends up in our sewage systems. And our sewage pipes, often made of clay, are getting on in years, so water seeps in through cracks and crevices.

The rate at which the urban Bay Area is adapting to these threats is lagging behind the rate at which rain is inundating it, Choksi-Chugh said. Cities need to invest in replacing pipes and upgrading wastewater treatment systems to increase storage capacity and install more recycling technologies, she said. Cities could also encourage homeowners to replace old pipes with grants or low-interest loans.

Without major improvements to our sewerage infrastructure, these dangerous spills will increase as climate change leads to more extreme weather, experts say.

“Our old infrastructure just won’t keep up,” said Choksi-Chugh. “It won’t be able to handle these major storm events year after year. So we really have to think about the future.”