Upgrading our System to Remove Nutrients

The San Francisco Public Utilities Commission (SFPUC) operates two of the 37 wastewater treatment plants across the region that discharge into San Francisco Bay. Our plants operate under federal and state permits. As climate change alters conditions in the bay, we are actively participating in a coalition of wastewater utilities, regulators, and scientists studying the bay and assessing the level to which nutrients, including nitrogen, should be reduced to protect the health of the bay. 

This is a regional issue, and it requires a regional approach. 

Leading on Nutrient Removal
Even before requirements are in place, the SFPUC is proactively committing to build new infrastructure to reduce nutrients in our effluent. San Francisco plans to invest $1.5 billion in treatment technology and facilities to substantially reduce nutrients discharged to the bay. This represents the largest and most consequential investment in nutrient removal by a Bay Area utility to date.  While that major project is being worked on, we are investing another $18 million in an interim sidestream nutrient removal project.    

Treasure Island 
Additionally, the SFPUC is currently building a new wastewater treatment plant on Treasure Island that includes state-of-the-art nutrient removal. Scheduled to be completed in 2026, the new facility was designed with nutrient removal facilities, including full stream nitrogen removal, which can remove around 80 percent of nitrogen during the secondary treatment process. 

Southeast Treatment Plant
Our Southeast Treatment Plant, which processes around 80 percent of San Francisco’s wastewater, is currently undergoing a generational upgrade. This includes an interim sidestream treatment process, which will remove nitrogen from the highly concentrated liquid wastestream from the dewatering of biosolids. This process may remove around 10-15 percent of nitrogen with a relatively small footprint.  The project is $18 million. 

The second project, Mainstream Nutrient Reduction, is budgeted for $1.5 billion. It is anticipated to provide significant long-term load reductions by constructing new facilities at the Southeast Plant.

The SFPUC will continue working closely with our partners on long-term strategies to meet potential nitrogen removal requirements as research and regulations evolve. These strategies would include construction of major new infrastructure and regional investment, which can only be accomplished in partnership with ratepayers, advocates, regional partners, and state and federal officials.