Riverdale • After a series of landslides, three Riverdale homes sitting on top of a steep and muddy slope were placed under mandatory evacuation Tuesday as city officials braced for more instability.

“It’s a very dangerous slide,” said Jared Sholly, the city’s fire chief, during a press conference streamed online by ABC4 News. “We need to keep people out of there.”

Police taped off the area surrounding the homes, near 4850 South and 600 West, and closed the road in front of the neighborhood. A fourth homeowner chose to voluntarily leave.

Residents reported the first mudslide on Nov. 19 and were temporarily evacuated before an engineer ruled out any leaks with the city’s water lines. Another two slides on Monday and Tuesday, though, prompted Riverdale to clear out the three houses closest to the precipice. Those backyards all face west, overlooking a canyon with railroad tracks and the Weber River Parkway.

City administrator Rodger Worthen said the slope was still “active” Wednesday and the evacuations have “an air of permanency.” Geologists reported that springs in the gully softened the dirt and caused heavy sloughing, covering about 300 yards.

“There are significant seeps and springs all along the toe of this bluff,” Worthen said. “They’ve been there for many, many years. … We can’t do anything, geologically speaking, to control the earth.”

He noted that city records include mention of the springs dating back to the 1960s. The land is privately owned. One of the evacuated residents has lived in her home for 41 years, Worthen said.

The area was quiet Wednesday, with few people walking around. Several U-Haul moving trucks were parked outside of homes, offering free storage for those impacted. Worthen said it’s possible more houses will need to be evacuated.

“It’s growing. It’s active,” he said. “That’s our concern.”