A sanitation district in eastern Contra Costa County has been fined a record $5.6 million for a sewage spill in Suisun Bay.
The San Francisco Bay Regional Water Quality Control Board approved the settlement with Delta Diablo for discharging more than 23 million gallons of untreated wastewater into marshland connected with the bay in 2024.
“This $5.6 million administrative civil liability is the largest penalty ever approved by the regional water board,” it said Friday in a statement.
Delta Diablo Sanitation District treats sewage for about 218,000 customers in Antioch and Pittsburg, and the unincorporated community of Bay Point, according to the district’s website.
The spill began around Nov. 5, 2024, when an underground line broke beneath a marsh, the water board said. It continued until being discovered on Dec. 2. Delta Diablo repaired a 20-foot section of the pipeline within two days, stopping the discharge by Dec. 4.
“Sewage spills of this magnitude pose serious risks to water quality, wildlife habitat, and public health,” said Eileen White, executive officer of the water board. “This settlement holds the discharger accountable while making critical investments to modernize infrastructure and reduce the risk of future spills.”
Most of the settlement will be used to install a new force main parallel to the existing pipeline at the Shore Acres Pump Station, the board said. The treatment plant will also retrofit its discharge outfall with check valve.
The water board said it calculated the penalty in accordance with the State Water Resources Control Board’s Water Quality Enforcement Policy.
Factors included the volume of the spill, the discharger’s response and corrective actions, and the potential effect on water quality, the board said.