Pima County said a Department of Transportation team cleared 800-pound boulders and some snow off the Mount Lemmon Highway to keep the road to Mount Lemmon open during the Martin Luther King Jr. holiday weekend.

“We need to keep at least one lane open in case of an emergency situation,” Rafael Tapia, public works crew supervisor, said in a posting on the county's website.

The Pima County Department of Transportation crew worked their way up the 25-mile highway that Sunday, clearing as they went. Later that night, the Sheriff's Department called the department to clear a rock slide that blocked much of the road in one area. As they cleared one rock slide, the discovered and cleared seven more.

“They often happen with the rainy weather more than the snow and seem to be more frequent after the two major fires that happened several years ago,” Joe Soto, public works manager for the DOT’s Maintenance Operations Division said in the posting. “This weekend was the first in a while where we had to close the roads due to rock slides rather than snow.”