Save the Bay official says stormwater is largest source of plastic and microplastic pollution to San Francisco Bay; outlines local steps

Josh Quigley, policy manager for Save the Bay, told a City of Sunnyvale sustainability speaker series webinar that urban stormwater — the runoff from streets and paved surfaces — is the largest contributor of many pollutants to the San Francisco Bay and a major pathway for plastic and microplastic contamination.

Quigley said the federal Clean Water Act and regional regulators require municipalities to stop discharging trash into waterways and that many Bay Area cities face a regulatory deadline at the end of June 2025 to demonstrate full trash control. “Full trash capture … 0 discharge is the goal under the Clean Water Act,” Quigley said.

The San Francisco Estuary Institute has estimated the Bay receives trillions of microplastic particles annually, Quigley said: “The Bay is actually receiving more than 7,000,000,000,000 microparticles of microplastics every year, and most of that is coming through our storm drain system.” He and other speakers at the webinar outlined three broad approaches cities use to meet the trash-control requirement: install engineered filtration devices that capture pieces down to about 5 millimeters; increase maintenance and street‑level controls such as sweeping and focused litter pickup; and reduce the amount of single‑use plastic entering the system through ordinances and industry changes.

Quigley described examples in Sunnyvale, showing the city’s…