White River National Forest Supervisor Scott Fitzwilliams was driving home from vacation on Aug. 10 when he glanced up and saw the plumes billowing out of Glenwood Canyon and knew a historic wildfire was coming.

It wasn’t just that the flames licking up the craggy canyon walls were threatening homes, a railroad, a major highway and a power plant. It’s that the now 25,000-acre-and-growing Grizzly Creek Fire was burning in the municipal water supply of Glenwood Springs and in the headwaters of the Colorado River watershed, which eventually slakes more than 40 million downstream users.