Dramatic mudflows were seen in Oak Glen and Forest Falls as the storm, which had been downgraded from a hurricane before it entered the region, soaked the area.
San Bernardino County issued a local emergency declaration in response to the storm. No injuries or were reported.
Valley of the Falls Drive was among the mountain roads that were rendered impassable after being covered with mud and debris.
Oak Glen resident Paul Forgues said, "It was a river down the road" from his home Sunday night, "with logs and boulders and everything."
Tropical Storm Hilary brings major flooding to Palm Springs and Coachella Valley
On top of that, there was a ruptured water pipe in one area and problems with fresh water.
"I've never seen a burst open and spray out," said resident Donna Dorcas.
On Monday morning, a shelter-in-place order remained in place for residents of Oak Glen Road, between Casablanca Street and Harris Road. An evacuation order was issued for the nearby Serrano Square neighborhood in Yucaipa.
Tropical Storm Hilary first made landfall in Baja California on Sunday in a sparsely populated area about 150 miles south of Ensenada. One person drowned. It then moved through mudslide-prone Tijuana, threatening the improvised homes that cling to hillsides just south of the U.S. border.
The first tropical storm to hit Southern California in 84 years, Hilary dropped more than half an average year's worth of rain on some areas, including Palm Springs, which saw more than 3 inches (8 centimeters) of rain by Sunday evening.
The Associated Press contributed to this report.