The Boulder County commissioners plan to talk about using drones to apply herbicides after receiving more than 800 emails in opposition and hearing from more than a dozen people during last week’s public comment session.

The opposition is in response to a planned aerial herbicide spraying of indaziflam in the Red Hill area at Heil Valley Ranch to control cheatgrass. The area is west of regenerative farms, including Yellow Barn and Elk Run farms.

The discussion is scheduled as part of Tuesday’s business meeting, which starts at 9:30 a.m. in Third Floor Hearing Room at the County Court House, 1325 Pearl Street, Boulder. To watch the meeting online, go to bit.ly/4iGM2zU.

Last year, the commissioners, on a 2-1 vote, agreed to move forward with a county weed management plan that allows the use of herbicides targeting invasive species on parks and open space lands. Commissioner Ashley Stolzmann, who wanted to completely remove herbicides as an option, was the dissenting vote.

The plan allows the county to use drones to apply indaziflam, a herbicide originally approved for use by the federal Environmental Protection Agency in 2010, in areas with cheatgrass, a widespread weed in the county that county staff members say can suppress native species and create a fire hazard. The plan targets cheatgrass in high biodiversity areas in rugged foothill terrain, including Rabbit Mountain, Hall Ranch and Heil Valley Ranch.

Parks and Open Space Deputy Director Stefan Reinhold said drones are used because they move at a slower, more controlled speed than helicopters, allowing for more precise spraying. The drones fly about eight to 12 feet above the ground and have downward force rotors and large droplet nozzles to reduce drift, he said. There’s also a 50-foot buffer from property lines and spraying won’t happen if wind speeds are above 10 mph, he said.

A recent notice that the county planned to apply the herbicide at Heil Valley Ranch prompted the Sierra Club’s Indian Peaks Group, Yellow Barn Farm and other advocates to encourage residents to send letters and speak at the commissioners’ recent public comment session. A local group also raised money to pay a lawyer to write a letter demanding a stop to the application.

Advocates say the herbicide will sterilize the soil for years, preventing all seeds — not just the cheatgrass seeds — from germinating. They’re also concerned that, despite the county’s precautions, the herbicide will end up in their soil or water. Instead of herbicides, several speakers urged using goats to control invasive weeds.

Regenerative farmer Carina Fisher called the decision to spray herbicides near farms shortsighted.

“We have experts, so much science, so much experience in this county and, instead of utilizing those resources, we’re outsourcing and feeding millions of dollars into an industrial complex that does not care about us,” she said. “It does not care about our futures. It does not care about our children.”

Resident Erin Meschke also urged the commissioners to protect local farms by not using herbicides.

“I want the quality of my food to be preserved and the time and effort my farmers put into naturally stewarding their land to be honored,” she said.

Following public comment, Commissioner Claire Levy said she already considered the concerns raised during public comment before voting last year in favor of the weed management plan, which is scheduled to be reviewed every three years. “I did my best to balance those competing interests to reach a decision,” she said.

But Stolzmann said she continues to not support using herbicides and was concerned other methods weren’t tried, while Commissioner Marta Loachamin said she had “grave concerns” based on public comment and requested a discussion.