Stop Boulder County, CO from Spraying Herbicide via Drones

Boulder County officials are planning to expose residents and wildlife to an herbicide called indaziflam, to be sprayed via drone over approximately 3,000 acres in the county starting as early as November 1.

While the long term effects of indaziflam are unknown, we do know that the herbicide poses serious health risks to both humans and animals and that its manufacturer, Bayer, has long been known for prioritizing profits over people.

Children are at increased risk of adverse health effects from toxic exposures and the planned blanket spraying via drone will leave no place to hide from what should be a completely avoidable toxin. This area is a crucial habitat for herds of elk and bighorn sheep that will also be at a potentially devastating exposure risk.

Routes of toxic exposure include through water run-off from steep slopes into rivers and creeks and also into groundwater to be used for crop irrigation, threatening the food supply as well.

Concerns about indaziflam are numerous, including:

• Per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” have been found in the formulation to be sprayed
• The formulation is a non-selective herbicide known to kill both weeds and native plant seeds
• It can remain in effect for four to six months or longer with some studies showing efficacy for multiple years in rangeland settings
• It can prevent all seeds from germinating for years, potentially impacting regrowth, especially in post-fire conditions

One of the stated legislative goals for 2026 on the Boulder County website is to “protect and enhance the health of the public and the environment.” Spraying a known toxic substance from the air is at complete odds with this goal.

A similar drone spraying plan was announced in 2025 but was paused following backlash from residents. We must act again – and quickly – to stop this toxic plan in its tracks.

Contact the Boulder County commissioners today to voice your concerns regarding the potential consequences from exposure to indaziflam.