Soon, weed-killing chemicals will start falling from the sky over the Red Hill area of Boulder county, Colorado.

The wildland is known for its biodiversity, home to hundreds of important species and a concentration of rare environmental resources. It is a key habitat for beloved herds of elk and bighorn sheep, with farms and ranchland lying at its base.

But any day now, hundreds of acres of Red Hill are set to become the target for drone spraying of a chemical herbicide that some researchers warn come with concerns.

County officials say the plan is an effective and essential move that will wipe out invasive weeds and mitigate the risk of dangerous and costly wildfires that could use the unwanted vegetation as fuel.

…