An Underexplored Pathway
Scientists have known for decades that stormwater runoff transports legacy contaminants like PCBs and mercury into San Francisco Bay. We have only recently begun to understand how stormwater also carries emerging contaminants like PFAS, plastic additives, and chemicals from vehicles and tires.
Four years of sampling stormwater found hundreds of emerging contaminants that flow down streams, city streets, and storm drains to the San Francisco Bay when it rains. The project spanned water years 2019–2022 and sampled both urban and minimally developed sites during storms. We analyzed five classes of contaminants: PFAS (“forever chemicals”), organophosphate esters (flame retardants), bisphenols (a common plastic ingredient), ethoxylated surfactants (a common cleaning ingredient), and tire-derived compounds. The urban stormwater contained a broad array of emerging contaminants, with concentrations often similar to municipal wastewater outputs. The wide-ranging concentrations we observed highlight the need for more data to estimate how much of these contaminants reach the Bay.
We also uncovered serious knowledge gaps about commercial products and their uses. Effective management is challenging because scientists know little about outdoor sources of emerging contaminants, like artificial grass, construction products, and paint, among many others.
Next Steps
Stormwater is still an underexplored way that contaminants move through the environment in the Bay Area and globally. Our current research will cost-effectively estimate how much of various contaminants reach the Bay. These findings will help manage and protect Bay water quality.
In urban to peri-urban watersheds such as those surrounding San Francisco Bay, stormwater runoff is a major pathway by which contaminants enter aquatic ecosystems.
As part of a maturing science strategy, the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) focuses on monitoring and modeling of emerging contaminants in major pathways in an effort to track Bay contaminants back to their sources and better inform management.
The overarching goal of the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) is to answer the highest priority scientific questions faced by managers of Bay water quality.
20 Years of Investigating Underregulated Chemicals
The Regional Monitoring Program for Water Quality in San Francisco Bay has grown into a world leader in studying under-regulated and poorly understood contaminants. The efforts have led to groundbreaking studies about forever chemicals, flame retardants, microplastics, pesticides, tire chemicals, and more—and inspired policy changes.
New Data on Salmon-Killing Chemical In San Francisco Bay
A new dataset on San Francisco Bay water includes some of the world's the first information about levels of the car tire chemical 6PPDQ in an estuary. Threatened steelhead trout may be susceptible to levels found in the Bay.
How Stormwater Studies Can Make the Bay Cleaner
As stormwater sampling across the San Francisco Bay Area reveals more poorly regulated chemicals, those who want clean water in the Bay face a tricky question: what can be done about it? The final part of a special feature series on stormwater monitoring.
When rainstorms wash contaminants into the Bay, scientists can only sample stormwater in a few places at once. Three years of inventing and testing have led to a solution in the form of 15 briefcase-sized robots, with names like “Captain Capture” and “Missus Sippy,” to slurp up samples without human supervision onsite.
The Storm Chasers: What Stormwater Reveals About Pollution In San Francisco Bay
SFEI’s stormwater monitoring team has grown and is innovating techniques to further expand its influential studies. Part one of a special feature series on stormwater.
Winning Stormwater Robot Names Selected
Meet Captain Capture, Pre Sipitation, and our 13 other stormwater sampling robots we named with help from the public.
Help Us Name Our New Stormwater Sampling Machines!
The SFEI stormwater team has developed robot samplers to pump up sips of stormwater runoff during rainstorms so we can test for pollution. Now, it’s prime time to name the 15 new samplers that we’ll deploy in the field across the Bay Area this upcoming wet season.
Vehicle Tires Threaten Water Quality
Update: On October 1, 2023: California Department of Toxic Substance Control (DTSC) 6PPD regulations became effective, making it the first government in the world to regulate the chemical content of vehicle tires to protect salmon. DTSC is requiring tire manufacturers to identify alternatives to the tire preservative that is the source of the chemical toxic to coho salmon.
