No one was hurt Saturday morning when a landslide in Maple Valley swept dirt and trees into the Cedar River. But as dirt continued to tumble down the slope, officials closed a half-mile stretch of the river until further notice.

The 10 a.m. slide temporarily blocked the river near Southeast 214th Street off Highway 169.

The clogged river flooded seven properties in the area, including part of a 20-acre property across the river from the slide, according to the Kent Fire Department. No one was evacuated.

The river quickly resumed flowing, but left six houses with minor water damage, fire department Captain Kyle Ohashi said.

“Fortunately, this is a rural area and there are very few homes for how many acres were affected,” he said.

The landslide — a triangle shape on the side of the hill — is roughly 300 feet across at the base and 300 feet high at its peak. Because many large fir trees are along the edge of the face, some dangling off the edge, Ohashi said, the site will need to be monitored closely.

“The large 100-foot fir trees, they are actually hanging down the hillside right now,” he said. “The first heavy wind or rain that we get, they could come down.”

With those overhanging trees and the hill’s incline made more steep by the slide, state geologist Dave Norman, who was on the scene Saturday afternoon, said there is no question that parts of the hill are going to continue to fall.

Because of that risk, the King County Sheriff’s Office ordered an emergency closure of the Cedar River — from Highway 169 at Highway 18 to Maxwell Road Southeast at Highway 169 — for all activities, including fishing, boating, floating and swimming.

This is not the first time a slide has occurred at this location. Norman said he could see the slope had failed in the past, but he was unsure how long ago. He also noted another failed slope 100 feet away.

“There should be a lot of caution with any steep slopes along the Cedar River,” he said.

The King County Sheriff’s Office will continue monitoring the area.

Coral Garnick: 206-464-2422 or cgarnick@seattletimes.com. On Twitter @coralgarnick