The sun sets behind Alcatraz and the Golden Gate Bridge, seen from Treasure Island in San Francisco Bay in Calif., on September 2, 2019. (Ray Saint Germain/Bay City News)

San Mateo County and nine of its cities and towns filed a lawsuit this week against the now-defunct Monsanto Corporation to recoup the costs of removing toxic chemicals the company allegedly left across the county.

The lawsuit alleges that Monsanto, the creator of the herbicide Roundup, knowingly contaminated the county with polychlorinated biphenyls, also known as PCBs, an organic chlorine compound that has been determined to be both carcinogenic and a pollutant.

The county and the cities and towns of Atherton, East Palo Alto, Foster City, Menlo Park, Portola Valley, Redwood City, San Carlos, San Mateo and Woodside filed the lawsuit Thursday, alleging that PCB contamination is common across the Bay Area, including Redwood City Harbor.

“There’s no reason in the world why our taxpayers should have to pay for the hundreds of millions of dollars we need to spend to prevent further PCB pollution and contamination,” San Mateo County Attorney John Nibbelin said in a statement. “That’s Monsanto’s responsibility, and that’s why we’re taking them to court.”

The U.S. government banned the production of PCBs in 1978. Monsanto was acquired by the German pharmaceutical giant Bayer AG in 2018 after being embroiled in multiple controversies over its chemical and biotechnology products, which were criticized as dangerous to environmental and public health. Monsanto was dissolved as a company that year as part of the sale.

In June 2020, Bayer agreed to pay more than $10 billion in settlements involving Monsanto products like Roundup and PCBs.

A Bayer spokesperson called the lawsuit “meritless” in a statement and argued that Monsanto never “manufactured, used or disposed PCBs,” in California.

“Where it has been determined that cleanups are necessary, federal and state authorities employ an effective system to identify dischargers and site owners and allocate clean-up responsibilities to them,” the spokesperson said. “Litigation of the sort brought by local governments risks undermining these efforts.”

The complaint filed by the 10 jurisdictions can be found at