Washington, DC —San Francisco’s sewage agency is building a new biosolids facility that will significantly increase nutrient loading in the San Francisco Bay, according to Public Employees for Environmental Responsibility (PEER). Despite growing concerns about rising nutrient levels linked to fish-killing algae blooms, the San Francisco Public Utilities Commission (PUC) has no firm timetable for implementing any process to offset this potentially disastrous side-effect.

The PUC is mid-way through a $3 billion modernization process that would, according to the agency, “produce a higher quality biosolids, capture and treat odors more effectively, and maximize biogas utilization and energy recovery.” However, this Biosolids Digesters Project uses a technology (called Thermal Hydrolysis Process or THP) that produces much higher levels of ammonia (a potent nutrient) than other treatment methods.

A similar plant serving the Washington DC metro area produced ammonia concentrations that were so elevated as to upset the balance of nutrients in Chesapeake Bay, an estuary comparable in size to the San Francisco Bay.

While the PUC has acknowledged this concern, it will not be effectively addressed this decade. In a January 31, 2023 Technical Memorandum to the San Francisco Bay Regional Water Quality Control Board, the PUC estimated that it “would develop an enhanced side-stream treatment facility” beginning in 2030 that would “take five to six years to complete.” This would cost an additional $115 million. In the meantime, an “interim side-stream treatment system” would be able to produce only “an approximately 20 percent reduction in the nitrogen load…”

“Facing the prospect of more toxic algae blooms, it is astounding that San Francisco’s current ‘worst in the Bay’ nutrient loading, could get even worse,” stated Pacific PEER Director Jeff Ruch, pointing out that that the City has not even calculated its future nutrient loadings from sewage outfalls. “San Francisco should not be allowed to activate its new Biosolids Digestion Facility until the full nutrient side-stream controls are in place.”

The precarious health of San Francisco Bay flows from weak water quality regulations that do not require reductions in nutrients discharged. Instead, the current Regional Permit only requires the Bay Area’s sewage agencies to monitor and report on the nutrient load they are imposing on the Bay. In addition, the San Francisco PUC has fiercely resisted efforts – often by litigation – undertaken by both the state Regional Board and the U.S. Environmental Protection Agency to tighten pollution controls on it discharges.

“The biggest threat to the health of San Francisco Bay is the leadership of the City’s Public Utilities Commission,” Ruch added. “San Francisco Bay desperately needs to be put on an enforceable pollution diet.

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