Caltrans spokesman Bob Haus on Friday (March 18) said that a worker recently mistakenly broadcast-sprayed herbicides in the area off Highway 84 near La Honda soon after the agency had promised to do only spot spraying there this year.

"We promised not to do any broadcast spraying," Mr. Haus said. "One of our staffers misunderstood the directives. He was doing some broadcast spraying," he said. "That was a mistake on our part."

"That won't happen again," he said.

Mr. Haus said that the spraying was done by employees "who thought we were doing the broadcast spraying that we used to do."

"We are doing something new," he said. "We're always looking for more effective ways of doing things, and sometimes there's a learning curve."

Patty Mayall, director of Protect Our Watershed San Mateo County, said "this 'mistake' is one more reason to end this toxic way of weed management." Ms. Mayall said the continued spraying also risks a "road accident spilling toxic chemicals into drinking water sources and contaminating our watershed."

Residents who live close to and use Highway 84 in rural San Mateo County said they saw Caltrans on March 2 applying herbicides in violation of the label instructions that say only workers in protective gear should be in the area when the chemicals are applied.

Residents were also upset that chemicals had been sprayed near ditches and drains when rain was forecast.

After years of pressure from residents, road users, environmental groups and ranchers and farmers to stop broadcast spraying, Caltrans said on Feb. 10 that it would try another way to remove roadside weeds along Highways 84 and 35 in rural San Mateo County -- manual removal of vegetation, plus some spot spraying.

Caltrans is working with the California Department of Forestry and Fire Protection (Cal Fire) and the California Conservation Corps to cut and remove low-lying tree branches, weeds and undergrowth to reduce the potential for fires, Caltrans spokeswoman Gidget Navarro said when the announcement was made.

Mr. Haus also clarified that the gear employees were seen wearing, white protective coveralls and hoods, is not required to spray herbicides. "It's because of the danger of poison oak," he said. Only long sleeves, long pants and footwear are required for protection, along with rubber gloves, according to the labels of the herbicides Caltrans had said it was applying -- Accord and Capstone.

Mr. Haus said the general rule followed by Caltrans about spraying herbicides when rain is forecast is: "If we are 24 hours in advance of anticipated rainfall of a half-inch or more, we don't spray."

There was rainfall that week, but it's unclear whether Caltrans' general rule was followed; 0.6 inches of rain was reported in the area by the end of the day on March 4.