GRAND JUNCTION, Colo. -- The search for three missing men who were caught in the massive mudslide on the Western Slope has been suspended and it might take well into the summer until recovery efforts can resume because of unsafe conditions, Mesa County Sheriff Stan Hilkey said Tuesday.
"We are basically in a recovery effort," Hilkey said at a news conference in Grand Junction.
The slide -- which is about 2 miles long, three-quarters of a mile wide at the top and more than 250 feet deep -- occurred Sunday night on the Grand Mesa near Collbran.
Clancy Nichols, 51, Danny Nichols, 24, and Wes Hawkins, 46, have been missing since the massive slide occurred and are presumed dead, and the families are aware of the situation, Hilkey said.
Hilkey said there continues to be a buildup of water at the top of the ridge into a depression where the slide occurred and there is major concern of another potential slide. Officials "are not comfortable with others on the slide currently," the sheriff said.
Officials are assessing whether a second slide would go farther than the original slide. If there is another slide, it could hit houses in the path, but as of Tuesday afternoon, no evacuations have been ordered.
"The big threat is what happens if we get another slide," Hilkey said. "We don't know right now. We don't have a crystal ball."
The depression of water -- which is 1,600 feet long, 300 to 400 feet wide and more than 100 feet deep -- has cut off flow of the West Salt Creek, said geologist Jonathan White of the Colorado School of Mines. And as runoff continues to build into the depression, it is putting pressure on the slope that it could fail again.
White said there are three scenarios with the reservoir, two of which would be the continue ponding of water that would cause another slide. The third scenario is the depression is more stable than is currently believed and the water could stay in place for years.
But White described the moisture as a "chaotic disturbed mass of Green River formation" that is "more like soil than a rock."
"It's highly unlikely it could remain permanently," White said. "The big concern is we will see a second pulse of debris coming down this existing landslide."
Added Hilkey: "It would be ideal if the water finds an escape route on top of the slide."
Landslides are not uncommon on the Grand Mesa -- "You see the entire Grand Mesa, it’s a slide. It’s the nature of the geology," Hilkey said -- but what is unusual about this slide is its enormity. Oil and gas drilling in the area are not linked to the slide, White said.
White said the formations are under constant wetting and weathering that turns the moisture into clay. Combined with the type of slopes in the area and weak geology, plus gravity and heavy rain and snowmelt runoff, at some point it reaches a threshold in which a tension crack likely opened and water flowed over the top and into it before it let itself go.
"We believe the runoff from the Grand Mesa is what triggered the slide," Hilkey said.
The three missing men were ranchers who were checking on why the water flow from West Salt Creek had ceased when the slide occurred.
"They were doing what ranchers do," Hilkey said. "When water is affected, it's important. And their presence in the basin was natural and expected."
It's believed the men encountered a smaller slide when the bigger, massive slide occurred. It's possible the men will never be found, with Hilkey describing that as a "worst-case scenario."
"The family has acknowledged that, we have acknowledged it, but it doesn't deter our interest in doing everything we can," he said.
White said the slide happened "quite rapidly. I wouldn't say minutes."
"In this type of scenario, I don’t think they had a chance to do anything," White said of the three men. "They probably saw a wall of mud and Earth come right at them, 170 feet high with the consistency of wet concrete. It’s a force of nature that’s really unbelievable when you think about it.
"It's an extreme event."
Hilkey said there has been "an enormous amount of care from the Collbran community" as well as from across the state and the country, with a lot of offers to help. For now, "We don’t need or can’t really use boots on the ground," said the sheriff, adding work is being done through the air.
Hilkey said search and rescue crews are available if the situation becomes more stable, but for now, crews are working to try to find out what the water at the top is doing and to predict any future movement of the slide.
"I'm sure they are very frustrated," Hilkey said of search and rescue crews. "They want to do this. They want to find people. They are ready, willing and able."
Hilkey said he talked with officials in Washington state, where a massive mudslide on March 22 in Oso killed at least 41 people. He said he received "great advice" on where to start searching for victims first, but the slides are different.
"Their slide was smaller in size, though greater in victim loss," Hilkey said, adding the search and rescue coordinator with the Washington slide "was extremely helpful."