Grizzly Creek Fire could impact Glenwood Canyon, Colorado River long after it's contained, experts say

Posted at 5:12 PM, Aug 19, 2020
and last updated 2020-08-20 14:55:34-04

GLENWOOD CANYON, Colo. — Colorado officials have called the Grizzly Creek Fire in Glenwood Canyon a national priority — not only does the wildfire continue grow in dry conditions and across steep terrain, it has kept Interstate 70 shut down for more than a week, blocking a major artery through western Colorado, where few detours exist.

But even if crews are able to get enough of a handle on the fire to re-open the interstate, the fire could have a longterm impact on Glenwood Canyon and communities down the Colorado River, environmental experts said Wednesday.

Paul Santi, a professor of geology at Colorado School of Mines in Golden, said the burning of vegetation through the steep, cavernous canyon could lead to more rainfall runoff and rockfalls, in an area where falling rock is already a frequent hazard.

"In the West, even though there's not a lot of vegetation, what's there really matters," Santi said. "So what that means is you're more likely to have mudslides, or debris flows. It's more likely to affect rock and rockfalls and other sorts of geologic hazards."

Santi said the Grizzly Creek Fire — or any fire that happens in the canyon — also can loosen more rocks and other materials, as the burning and temperature changes create more cracking along surfaces. Vegetation will recover, but it could take several years to stabilize the soil after a large fire, Santi said.

"Glenwood Canyon is a spectacular area, and the reason it's spectacular is because it's deep and dangerous," Santi said. "There will never be a time before or after a fire when Glenwood is completely safe."

Santi said the way to make the canyon safer is what the Colorado Department of Transportation already does with rockfall mitigation efforts, such as removing unstable rocks and identifying rocks that may have become unstable during a fire. Crews can also bolts unstable rocks into place and put up mesh fences to catch falling material.

"That's the tradeoff of living in Colorado," Santi said. "We have beautiful mountains, but the mountains are out to get us."

CDOT spokesman Matt Inzeo on Wednesday said several issues are posing a challenge along I-70 in the canyon. There's still active burning alongside the highway, and as far as rockfall goes, crews haven't been able to assess some areas because the fire isn't contained. Officials have not given a timetable on when I-70 might re-open.

"There's a lot we don't know yet because this is still ongoing," Inzeo said.

Another concern ties into the changing landscape a wildfire can bring.

In the canyon, less vegetation could lead to more rockfalls. But beyond the canyon, burn scars could also cause problems, said John Berggren, a water policy analyst with Western Resource Advocates.

"My concern is not what happens in the next month, because the fire will do its thing," Berggren said. "My concern is next summer, and the summer after that, and the summer after that. Because we can get pretty heavy rainstorms in Colorado throughout the summer, and if you get a significant rain event on this burn scar that could cause all sorts of runoff."

The runoff, in some areas, could cause a debris flow that shuts down I-70 again or causes water quality issues in the Colorado River, which flows through the canyon and into farmland on the Western Slope.

"If I was a farmer in the Grand Valley right now," Berggren said, "I would be a little nervous each time it rained for the next few years."

The geological and environmental changes aren't limited to the Grizzly Creek Fire. Further west — and north of Grand Junction — the Pine Gulch Fire exploded Tuesday night, growing more than 37,000 acres to 125,000 acres, the second-largest fire in Colorado history.

From his backyard in Berthoud, geologist Uwe Kackstaetter, a professor at Metropolitan State University, has experienced some phenomenal sunsets as of late, calling them "an awesome side effect" of the fires across the state.

But the fires, Kackstaetter knows, are also creating devastating effects. Kackstaetter said the Pine Gulch Fire is so intense it is essentially baking the earth and destroying vegetation.

"Think about it this way," Kackstaetter said. "We have clay soil. You put this clay in the furnace and it makes terracotta. Something solid and no water gets through there. Or very, very little. So you have increased runoff and then you get these devastating floods."

The Pine Gulch Fire grew so intense Tuesday night that it created its own weather system.

"Very much so, because the fire is so hot,” Denver7 chief meteorologist Mike Nelson said. “You get all kinds of rising thermals, columns of air — like a hot air balloon, but on steroids."

Nelson said the air rushing in is how pyrocumulus clouds were created overnight Tuesday, producing lightning for several hours.

And as environmental and geological experts warn of the longterm effects of the fires, the crews on the ground still have a long battle ahead.

"The 90-day forecast," Nelson said, "is warm and dry."