COLLBRAN, Colo. — Authorities on Tuesday called off the search for three ranchers who disappeared after a huge mudslide in a remote part of western Colorado.Mesa County Sheriff Stan Hilkey said the slide remained too unstable to continue looking for the men.The three men were checking on problems with an irrigation ditch caused by an initial slide Sunday when a second, much larger slide hit. Authorities say the slide is a half-mile long and about 3 miles long.Hilkey said another slide is still possible.“We’re not able to do what we would like to do,” the sheriff said. “What we would like to do is have every inch of this covered with people if we could. But we don’t want to create any more of a tragedy than we already have.”The three men — a county road worker, his son and another man — were all from the close-knit town of Collbran. They volunteered to investigate when a rancher noticed his irrigation ditch stopped running.The smaller mudslide was found to be to blame for the water cutoff.When the men went to check on the damage, a huge chunk of the ridge sheared off, likely overwhelming them.Hilkey has said the slide was most likely triggered by runoff from Grand Mesa following two days of strong rain.No structures or roads were affected in the remote area, about an hour east of Grand Junction. A drone was used to try to detect heat sources from the missing near the edge of Grand Mesa, one of the world’s highest flat topped mountains.