(CBS4) – Once again Sunday, mud came cascading down in Glenwood Canyon, forcing the closure of Interstate 70 for a second time in a busy Colorado summer weekend. The slides shut down a major artery to and from the Western Slope and had people in Glenwood Springs waiting again.
The storm had crews preparing for days.
“The Grizzly Creek rest stop had been closed already for two days in anticipation of this,” said Jonathan Godes, mayor of Glenwood Springs.
On Saturday the highway was shut down for over seven hours as crews cleaned up a slide that was over 70 feet wide and 5 to 7 feet deep.
Get used to it.
The 2020 Grizzly Creek Fire is not done causing havoc.
“In a place like Glenwood Canyon where you have limited access and limited communication in terms of cellphone coverage, and that thing it’s a challenging, challenging environment,” said Bob Group, CDOT’s Geohazards program manager.
Group and his team try to navigate difficult slopes for a good look at potential risks, but in the canyon it’s not easy.
“Every situation’s unique,” he noted.
CDOT teams look at numerous issues when considering slide risks.
“There’s the burn severity, there’s the soil conditions, there’s the topography, there’s the rainfall intensity. There’s the rainfall duration. And all of those things combine,” said Group.
Some of the super-heated soil was burned in such a way that it no longer will absorb water. It’s called hydrophobic soil.
“There’s the root systems that are in place, but then there’s the aspect of the fire changing the nature of the soil itself and making the infiltration of water more difficult. Water that would have flowed into the ground before doesn’t have anywhere to go,” said Group.
In some place in Colorado there are mitigation efforts that can help.
“You can have sediment basins that you can put in. There’s the debris barriers that you can install and those are basically big steel mesh strainers.”
But in Glenwood Canyon, they won’t really do the job at the 30,000 acre Grizzly Creek fire burn scar.
“Both of those things require a footprint in an area that’s large enough and flat enough,” he told us.
And for the mesh strainers, “You really want to those to be installed in an area where you have access to maintain those because a single event can often fill those up.”
But access is not easy in steep Glenwood Canyon.
“Our fallout is Grizzly Creek and No Name — those drainages are our raw water intake,” said Glenwood Springs mayor Godes.
The city had to make some quick adjustments.
“There’s so much debris and turbidity and all kinds of nasty stuff that came down that we had to shut off our raw water intake and rely on the existing stocks of water that we have in our tanks and in the water processing plant at that time.”
Glenwood’s 6 million gallons of storage would be fine in the winter when water use is about 1 million gallons a day, but not in the summer when that increases to about 4 million gallons a day, mostly due to lawn watering.
The City put out a message early Sunday morning asking people to stop lawn watering.
“We had to send it out because we needed that irrigation to stop,” said Godes.
The slide late Sunday was worse.
“We had to extend the outside water restrictions to June 30 as one of the slides hit our water intake. This is actually a much more significant event than the one yesterday,” messaged Godes late Sunday evening.
Glenwood Springs also draws water from the Roaring Fork River, which makes its way over to Glenwood Springs from Pitkin County, carrying the water of the Crystal River with it. The water quality isn’t quite what Glenwood Springs gets from Glenwood Canyon already, but it’s become worse in recent years.
“There was a massive fire 3 years ago, the Lake Christine Fire in Basalt, and it is a pretty wide-ranging thunderstorm yesterday and we got a lot of debris flow from that burn scar that happened 3 years ago.”
Glenwood Springs is looking at long term water demand and may ultimately change rules on landscaping, said Godes.
“Lawns are just a massive water suck,” he explained. “We’re going to be looking at that through our municipal code. “I think the future is going to be for communities like Glenwood Springs is that we’re not going to be able to have golf course sized or conditioned lawns.”
But he also believes fewer wildfires would help. Many including the Grizzly Creek Fire and Lake Christine Fire are human caused.
“If we can avoid Lake Christine fires, Grizzly Creek fires or the current fires that are active right now in and around our town, the Oil Springs fire and the Sylvan Lake fire, that, that’s probably the better of the two.”