Baykeeper Update

Minimizing Pollution from a San Rafael Sewage Treatment Plant

Central Marin’s wastewater treatment plant needs stricter limits on its releases of raw sewage into San Francisco Bay during storms, Baykeeper recently told regulators.

Baykeeper urged the Regional Water Quality Control Board to tighten up the Central Marin Sanitation Agency’s permit to discharge treated wastewater into San Francisco Bay. The board is currently considering the renewal of the permit.

The plant, located in San Rafael, uses a multi-step process to treat sewage from 129,000 Marin County residents, several major industrial sites and San Quentin Prison. Each day, it discharges approximately 10 million gallons of treated wastewater deep into the central Bay.

During storms, however, large amounts of rainwater seep into the pipes and systems that collect sewage and route it to the treatment plant. When the increased volume of water exceeds the plant’s capacity, the plant operators mix raw sewage with treated wastewater and release the mixture into the Bay.

The plant recently made several improvements that should increase its capacity to keep untreated sewage out of the Bay. For this reason, Baykeeper advised the Water Board to tighten standards on the plant’s releases of the raw sewage mixture and require more testing to assure the tighter standards are met.

In addition to advocating for tightening controls on the treatment plant, Baykeeper advised the Water Board to better regulate all the upstream sewage collection systems that route wastewater to the Central Marin plant.

The collection systems are the main cause of the sewage problems during storms, because many of their pipes are old and in poor condition, which allows rainwater to infiltrate the pipes and overwhelm the plant’s capacity. So the collection systems should also be required to obtain pollution permits under federal law. This would allow a citizen organization like Baykeeper to enforce the Clean Water Act against these collection systems to stop contamination of the Bay.

The Central Marin treatment plant has conducted a U.S. EPA-required study of possible alternatives to discharging untreated sewage into the Bay. We pointed out to the Water Board that they are violating EPA policy because they have not made this study available for public review.

The Water Board will consider adopting the treatment plant’s permit in June. Baykeeper will continue to advocate for stronger controls on this facility’s wastewater discharges into the Bay.