CLACKAMAS COUNTY, Ore. (KOIN) — Officials are sounding a new alarm as torched land across Oregon is now primed for a different kind of disaster: flash floods.
Heavy rain began falling Thursday night, which could trigger flash floods and dangerous debris flows up and down the entire Cascades. Landslide and flash flood warnings aren’t uncommon during winter months but they can be especially problematic for areas burned by wildfires.
“This happens a handful of times every winter,” explained Bill Burns, an engineering geologist at the Oregon Department of Geology and Mineral Industries. “But in this case, it happens to overlap in these areas with recent wildfires.”
Wildfires remove vegetation and add layers of debris like ash and wood — materials that are easily eroded during bursts of heavy rainfall, thus making landslides more likely, Burns said.
Landslides and debris flows can travel with avalanche speeds and hit with little or no warning. Debris flows can travel miles from their source, don’t always stay in stream channels and can flow sideways and downhill.
“Where these occur generally are at the mouths of the canyons so where the canyon comes out onto the flat valley floor underneath very steep, vertical cliffs — the debris flows come out of the mouths of those canyons,” said Burns. “If people live in these areas or are passing through these areas during these periods of rainfall that we are going to have in the next 24 hours or so, they should be really cautious.”
In Clackamas County, officials warned of the danger to the Highway 224 corridor between Estacada and Ripplebrook and urge people to avoid the area. People in Marion County are also at risk.
A wildfire destroyed Shawnee Selmer’s home in Mill City. Selmer and her family went back on Sept. 12 to see what remained.
“Even when we were up there, everything was just shifting down and just falling,” she told KOIN 6 News. “Because we lived on a cliff, everything just is kind of going to shove off a cliff, it looks like — all the houses that are burned.”
Selmer’s family hopes rain will put out the fires and stop short of causing any more chaos. A GoFundMe has been launched to help Selmer and her 2-year-old child get back on their feet.
Further south, utility work was suspended in the Holiday Farm Fire area starting Thursday afternoon. Authorities said utility crews and non-essential people should keep out of Level 3 evacuation areas and areas scorched by the fire until at least Friday evening. Only crews directly related to the Highway 126 snagging operation or Leaburg dam operations will be allowed into fire areas during this time, officials said.
Remember: debris flows can move faster than you can run. Warning signs include unusual sounds like trees cracking or boulders knocking together and faint rumbling. Stay informed on the weather in your area and be vigilant. For some, the danger of landslides and flash flooding may mean a second evacuation.
If you find yourself in the path of a landslide, officials say to run uphill as fast as possible. Avoid river valleys and low-lying areas and never cross bridges if you see a flow coming toward you.