Mudslides triggered by quick-moving storm; residents escape its ‘full force’ | AspenTimes.com

Mudslides triggered by quick-moving storm; residents escape its ‘full force’

Heather McGregor
Special to The Aspen Times

The four-wheel-drive Subaru of Mitchell Creek resident Ann Martin sits wedged between boulders Tuesday morning as county crews clear debris from Mitchell Creek Road. Kelley Cox photo.

A mudslide that swept down Mitchell Creek Monday night was mobilized by a thunderstorm that dropped from one-third to one-half of an inch of rain in less than a half hour.

“We caught the edge of that storm. We didn’t get the full force of it,” said Bill Kight, community liaison for the White River National Forest.

According to rain gauges scattered throughout the area, the sudden storm dropped .3 inch of rain at the mouth of Mitchell Creek and at the Bowles Ranch on lower Mitchell Creek; .48 inch at the Glenwood Springs Fish Hatchery; and .28 inch on the rim of Mitchell Creek basin at 9,000 feet.

Across the Colorado River and to the west, the storm dropped .67 inch near the head of SOB basin near South Canyon.

The storm didn’t fully scour the steep slopes burned two months ago by the Coal Seam fire.

After taking a helicopter tour over the basin early Tuesday, Glenwood Springs Electric Department manager John Hines said most of the mudflows came off the west and north slopes of Mitchell Creek basin, while less came from the south and east slopes.

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That meant the above-ground electric line his crews rebuilt this past week up to the Besler property survived.

“Each draw collected water and made mud,” he said. “I just knew we were going to lose those poles, but we didn’t.”

And Hines said more mud flowed in the lower part of the basin than higher up.

“Three lateral channels have released their material,” said Andrea Holland-Sears, a Forest Service hydrologist, referring to side drainages in the basin.

“If we get more rain, there could be more material released, but it’s a harder geology up there” she said of the higher reaches of Mitchell Creek basin. “The west side still has the potential to flow because it’s mostly sandstone, which is less stable.

“We’re not out of the woods yet.”

The 150 families evacuated from their homes Monday night were allowed to return at noon on Tuesday, although the afternoon was filled with the fear of another thunderstorm and many stayed at home only briefly.

The National Weather Service posted a flash flood warning, but Tuesday’s storm came and went without doing further damage in the burned areas of West Glenwood.

Sizing up the slide, Kight believes it could have been much worse.

“We were real fortunate there wasn’t more damage from the mudflow,” he said.

No one was injured, but several vehicles in the area were damaged by the mud.

Rocks and mud trashed part of the Bowles family’s pasture and filled the yards and driveways of several other Mitchell Creek residents.

The strangest phenomenon of the event appears to be a wall of mud and rocks from six feet to eight feet high and running at least 60 feet along Mitchell Creek Road above the Glenwood Springs Fish Hatchery.

Kight said the debris was deposited just short of the creek, averting what could have been a far more serious flood downstream.

“We don’t know why it didn’t flow into the creek. It just came down the road like it was supposed to. Little things like that really spared us from more damage,” he said.

As it is, county road crews will be able to clear off the pile using loaders and trucks. It’s a lot of work, but is far better than the damage that could have resulted.

Kight credits the work done over the past six weeks by Dan Sokal of the U.S. Bureau of Land Management in stabilizing a steep and badly charred hillside on the east side of Mitchell Creek.

Some of the work is easy to see – a broad mat of pressed straw high on the slope, holding the loose soil underneath and encouraging new growth.

What’s harder to see are the hundreds of straw wattles, rolls of straw staked at intervals across the hillside. On close inspection Tuesday, Sokal found that about one-third of the cavity behind the wattles was packed with mud.

“It worked,” Kight said. “They kept a lot of flow on the mountain instead of down in the creek.”

Across the river, two gullies on the western side of Red Mountain released mudflows Monday night.

One drained onto West Midland Avenue at the railroad underpass, and city crews were busy cleaning up that mess Tuesday.

But very little mud flowed into the massive debris basins built behind the new Glenwood Springs Municipal Operations Center.

Instead, the rain swept black ash into the basin, streaking the back side of the barren trench and pooling a few inches in the bottom.

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