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The heavy storms that soaked the Bay Area last October ended fire season and brought hope — dashed during dry winter months later — that the state’s drought might be ending.
But while millions of people were celebrating the downpour the week before Halloween, the rains also caused an environmental headache in the East Bay, overwhelming a wastewater treatment plant and sending 16.5 million gallons of partially treated sewage into San Francisco Bay.
On Monday, state regulators and the East Bay Municipal Utility District, a government agency that operates the plant at Point Isabel in Richmond, agreed to settle the case in a deal that requires the district to pay $816,000 for violations of clean water rules.
“Our mission is to protect public health and San Francisco Bay,” said Andrea Pook, a spokeswoman for East Bay MUD. “We regret that this occurred.”
East Bay MUD treats the sewage of 776,000 people living in Alameda, Albany, Berkeley, Emeryville, Oakland and other communities.
The storms on Oct. 24 and 25 were unprecedented. An atmospheric river dumped 5 inches of rain over Oakland — nearly 30% of the city’s entire yearly average — in two days. The Oakland Hills got 9 inches in 48 hours, and Mount Tamalpais in Marin County got 16 inches.
In the East Bay, as in cities across the United States, heavy rains can cause major problems for sewage treatment plants. Rain water soaks into the ground, entering old sewer pipes through cracks and gaps. It surges and flows to sewage treatment plants, sometimes overwhelming them and causing spills.
To try and limit that problem, EB MUD, which provides drinking water and wastewater treatment to parts of Alameda and Contra Costa counties, runs three overflow plants.
The concept is simple: When heavy flows from storms overwhelm the system, some of the wastewater is diverted away from the district’s main plant in Oakland near the Bay Bridge to the three “wet weather” plants, where it is stored in tanks. The facilities can treat it to basic standards, called primary treatment, where workers use filters, screens and chlorine, before releasing it into the bay. Without treatment, raw sewage can carry disease that make people sick, and can harm fish and wildlife.
On the weekend of Oct. 23 to 25, it rained so hard that 557 million gallons per day of wastewater flowed into East Bay MUD’s system, more than 10 times the average in a normal day.
At one of the district’s three overflow plants, the Point Isabel Wet Weather Facility on the Richmond shoreline, workers ran out of a key chemical called sodium bisulfite during the storm. The chemical is used to take chlorine out of the wastewater before it released into the bay. High levels of chlorine can be toxic to fish and other aquatic life.
“There was a staff error,” Pook said. “They used more chemical than needed, so we used up our supply sooner than expected.”
As workers frantically called their chemical supplier at night, not getting more until the next morning, they released 16.5 million gallons of partially treated sewage into the Richmond Inner Harbor — 3.8 million gallons of which had levels of chlorine more than 10 times above the legal limit — and much of the rest with elevated levels of coliform bacteria.
East Bay MUD “failed to properly operate and maintain” the plant, according to the San Francisco Bay Regional Water Quality Control Board, a state agency that regulates water pollution. But because so much water was pouring into the roiling storm-hammered bay that weekend, diluting everything, the spill caused “a low threat of harm” and “likely no actual harm” to fish and wildlife.
The district posted signs the next morning around the Albany and Richmond shoreline, warning the public that the bay waters might be contaminated and pose a health risk.
In the settlement agreement, the regional water board noted that East Bay MUD had two similar violations in the past five years, with $137,000 in penalties.
Environmentalists said they supported the enforcement action. But they also called on East Bay MUD to do more to reduce the sewage surges into the plant, something that was called for in a 2014 lawsuit settlement.
“The agency is supposed to be better investing in nuts and bolts maintenance to fix their aging sewage infrastructure and deal with large volumes of stormwater infiltration,” said attorney Sejal Choksi-Chugh, executive director of Baykeeper, an environmental group that sued East Bay MUD a decade ago over sewage discharges.
“And now would be the time,” she added, “for them to also modernize their system to recycle and reuse as much wastewater as possible in the face of extreme droughts.”
Pook said the district has been working to reduce sewage flows during storms with efforts to replace old sewer pipes and other programs.
“We have made some changes,” Pook said. “We have improved the supply of chemicals and improved operator training so that we can prevent this from happening in the future.”
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