On Wednesday, Mesa County officials transitioned to a Level Two response to the West Salt Creek landslide. Conditions that prompted a Level One response last week are continuing.
According the Mesa County Emergency Action Plan drafted for the landslide, three levels of response can be initiated. Level Three is the highest alert level. The Level Two designation is a proactive step to be ready for an event, should it occur. Last week, officials noticed the appearance of a stream below the pond. That prompted the Level One response designation.Level Two in the plan calls for immediate notification of the public when conditions become hazardous to citizens. Residents along Salt Creek Road and the town of Collbran were made aware of the Level Two designation via a reverse 911 call on Wednesday morning, due to the possibility of water spilling over the pond or flooding the debris field through a different route. Although Collbran Town Manager Davis Farrar said the action was premature and sent out accidentally.
According to Mesa County Emergency Manager Andy Martsolf, the Level Two increase is a sign that something is likely to happen in the low-lying areas.
“We’ve been in a heightened state of awareness, but what this does is puts residents in low-lying areas on alert that something is likely to happen,” said Martsolf. “The magnitude of this event is unknown, but residents should be prepared to move to higher ground. What we’re seeing with the West Salt Creek Landslide is nature correcting what happened last year.”
The cataclysmic event on the Grand Mesa occurred on May 25, 2014, and took the lives of Wes Hawkins, Clancy Nichols and his son Danny Nichols. The landslide created a mud and debris field 3 miles long and ¾ of a mile wide. What officials call a “sag pond” was formed from rainwater, snowmelt and other runoff near the top of the slide.Recent rainstorms and heavy snow melt runoff is rapidly filling the sag pond. Storms in the forecast for this weekend combined with peak runoff could push it over the edge. The National Weather Service in Grand Junction has issued a flash-flood watch for the West Salt Creek landslide area in effect through Monday.
Martsolf predicted, “We will see some sort of event between Thursday and Sunday.”
If that happens, it is possible to see rapid down-cutting of the “slump block,” or debris field. This type of event may release a large volume of water that may impact Salt Creek Road and Collbran residents.
In an article in today’s Daily Sentinel, Mesa County engineering manager and the Salt Creek landslide incident commander Pete Baier said the prospect of a wave of tropical moisture was a significant factor in deciding to issue the warning and stage equipment to deal with flooding.
Officials anticipate the water in the pond will come out through an old creek bed and make its way down into the slide, Baier said.
Hydrologists estimate that the pond contained about 400 acre-feet of water, though it’s unlikely that all of that would come down at once, Baier said.
How much might come down, however, is a major question.
“No geologist in the world would venture to tell you how consolidated” the block of earth clinging to the side of the mesa is, Baier said.
“We’d rather be out in front” of a spill with warnings and equipment at the ready, Baier said.
If the pond overflows, it will likely reach West Salt Creek and the Plateau River, causing overflowing and flooding for those that live in those areas.
Tony Shrope’s home and business is located along the Plateau River, currently a high risk flood zone.
“I’m going to throw all my money in the safe, I’m going to grab my computer because that has my photos, videos, and I’ll go up to my parents. They live on the hill,” said Shrope, as he prepared to evacuate. “Just given the layout of the business, if the water comes across the road, it’s going to pour probably right down into my store.”
The Mesa County warning comes on the heels of a wetter than normal spring.
“We’ve had such horrible weather from a horrible winter and a wet spring, so the traffic flow has been minimal,” said Shrope. “We were looking forward to summer and it started off okay but now we get this bad news so it’s just one thing after another. I just hope it doesn’t happen, I was looking forward to having fun this summer.”
Mesa County is providing sandbags for people in low-lying areas.
The Town of Collbran is about six miles northwest of the landslide. Part of the mud and debris field covers property owned by the U.S. Forest Service; the remaining land belongs to private landowners. Because of the instability of the slide area, the U.S. Forest Service restricted area remains in place, including the landslide debris field and 300 yards from the edge of the debris field.