San Francisco Bay Water Board approves $5.6 million penalty for sewage spill to Suisun Bay

OAKLAND – The San Francisco Bay Regional Water Quality Control Board has approved a $5,557,700 settlement with Delta Diablo, a wastewater treatment agency serving eastern Contra Costa County, in connection with a sewage spill that released more than 23 million gallons of untreated wastewater into marshland connected to Suisun Bay.

The spill began around Nov. 5, 2024, and continued for nearly a month before being discovered on Dec. 2. It originated from a subsurface break in the Shore Acres Force Main beneath a marsh, which delayed detection. 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 San Francisco Bay Water Board. “This settlement holds the discharger accountable while making critical investments to modernize infrastructure and reduce the risk of future spills.”

Sewage spills can introduce harmful bacteria and pollutants into waterways, posing risks to public health, recreation and wildlife habitat. This incident underscores the importance of continuous monitoring, regular inspections and proactive maintenance of wastewater infrastructure.

Most of the settlement funds will be used to install a new force main parallel to the existing pipeline at the Shore Acres Pump Station. This upgrade will allow for replacement of the aging pipe while adding redundancy and increasing operational flexibility.

Additional funds will support improvements at Delta Diablo’s wastewater treatment plant, including retrofitting the discharge outfall with “duckbill” check valves. These upgrades are expected to improve effluent mixing, reduce sediment and aquatic organism capture, and prevent flow reversal at the outfall

The regional water board calculated the penalty in accordance with the State Water Resources Control Board’s Water Quality Enforcement Policy. Factors considered included the volume of the spill, the discharger’s response and corrective actions, and the potential impacts to water quality and beneficial uses.

This $5.6 million administrative civil liability is the largest penalty ever approved by the regional water board.

More information about the regional board’s enforcement actions can be found here.

The San Francisco Bay Regional Water Quality Control Board works to preserve, enhance, and restore California’s water resources to protect public health, the environment, and beneficial uses for current and future generations.