Clackamas County faces increased landslide risk in wildfire areas as more rain expected

Officials in Clackamas County are warning residents to be aware of increased risks of landslides over the next week as heavy rains fall on areas scorched by wildfires earlier this year.

The Riverside fire burned more than 130,000 acres in the county over several weeks in September, leaving many hillsides without protective plant cover that serves to hold soil in place.

“When heavy rains hit those hillsides, they could fail, causing mud and debris to enter creeks and rivers,” Jay Wilson, Clackamas County resilience coordinator, said in a statement. “That could increase chances of landslides or flooding downstream or at the bottom of barren hillsides.”

Landslides can move quickly, faster than a human can run, and have been known to travel miles. Along the way, mudflows can pick up large objects, such as trees and boulders, as they barrel downhill.

Scorched earth also does not absorb rainfall as efficiently as unburnt soil does, so increased runoff can swell streams, creeks and rivers, increasing flood risk.

“A heavy rainstorm is also a great reminder of the need for property owners to consider flood insurance,” Wilson said. “There’s a 30-day waiting period for protection to take effect. Please consider flood insurance immediately.”

The National Weather Service has called for rains to taper off Friday with a mostly dry weekend, but precipitation is likely to return next week.