In response to concern from the community, Caltrans officials say they have cut back on the frequency of broadcast spraying of herbicides. In exchange, they have switched over to spot spraying and more mechanical measures, such as mowing, and are using less toxic solutions than in generations past.
Still, many Coastside residents remain wary of the host of chemicals used in the process of roadside spraying. The chemicals include aminopyralid — shown to adversely affect vegetable crops when it remains in the soil — and glyphosate, which has been classified as a probable carcinogen.
An online petition against Caltrans’s use of broadcast spraying in San Mateo County currently boasts nearly 500 supporters on Change.org with around 75 written signatures.
Patty Mayall, who lives near Highway 84 in unincorporated San Mateo County near La Honda, has led the charge on efforts to stop the spraying. She argues that the weeds can be handled strictly through mowing or other nontoxic methods such as applying dry ice to the base of the invasive plants.
Mayall said that Marin County is ahead of San Mateo County in its efforts to control weeds without the use of herbicides and believes her county could take a leaf out of the Marin playbook.
“Marin is way ahead. They’ve been doing this for years,” Mayall said.
In fact, the San Mateo County Board of Supervisors banned broadcast spraying of herbicides in 2012 with the exception of the county’s airports. Yet Caltrans continues to spray along some San Mateo County roads, including Highway 1 and Highway 84.
The former was sprayed on the South Coast during the Half Moon Bay Art and Pumpkin Festival weekend, the latter was originally set to be sprayed in November. That roadway will most likely be sprayed sometime in February, said Caltrans spokesman Bob Haus.
In November, Caltrans held an open house of sorts to share information about plans to spray on Highway 84. Caltrans officials have noted that the roadside weeds prove a hazard to bicyclists and motorists when they block visibility on the roadway and that they often receive complaints from the public asking Caltrans do something to control the weeds.
Mayall expressed concern that the “no spray” signs she and others have posted have not been honored and that the agency’s plans to spray are unpredictable.
“Spraying can be happening anytime,” Mayall said, citing the unannounced spraying on Skyline Boulevard and on Highway 1. “We don’t know when, we don’t where. We usually don’t know what they’re spraying until after the fact.”