Landslide alert issued for Central, Eastern Oregon due to Tropical Storm Hilary

The Oregon Department of Geology and Mineral Industries warns that landslides will be possible in Central and Eastern Oregon as record rainfall and flash flooding will be possible through Monday evening due to a rare surge of tropical moisture produced by Tropical Storm Hilary. Landslides and debris flows are known to occur in areas of steep terrain and recent wildfire burn scars.

PORTLAND, Ore. (KOIN) — The Oregon Department of Geology and Mineral Industries warns that landslides will be possible in Central and Eastern Oregon as record rainfall and flash flooding may happen through Monday evening due to a rare surge of tropical moisture produced by Tropical Storm Hilary.

Landslides and debris flows are known to occur in areas of steep terrain and recent wildfire burn scars.

The National Weather Service has issued flood watches for areas of Western and Central Oregon, including the Grande Ronde Valley, the Northern Blue Mountains of Oregon, the Southern Blue Mountains of Oregon, Wallowa County, Baker County, Harney County, Malheur County, the Oregon Lower Treasure Valley, John Day Basin and the Ochoco-John Day Highlands. The flood watches will remain in effect between Sunday evening and Tuesday afternoon.

“Debris flows are rapidly moving, extremely destructive landslides,” the Oregon Department of Geology and Mineral Industries stated Sunday. “They can contain boulders and logs transported in a fast-moving soil and water slurry down steep hillsides and through narrow canyons. They can easily travel a mile or more. A debris flow moves faster than a person can run. People, structures, and roads located below steep slopes in canyons and near the mouths of canyons may be at serious risk.”

The heaviest rain is expected to fall Monday morning across Malheur and Baker counties, in Payette, Wash., and in Adams, Gem, and Canyon counties in Idaho, the NWS predicts.  As much as 4 inches of rain will be possible per hour at the height of the storm.

If you expect to be in these affected regions during this time, DOGAMI recommends taking the following safety precautions:

• Stay alert. Track the flood watch by radio, TV, weather radio or online. If told to evacuate, do so immediately.
• Listen. Unusual sounds might indicate moving debris, such as trees cracking or boulders knocking together. A trickle of falling mud or debris may precede larger landslides. If you think there is danger of a landslide, leave immediately.
• Watch the water. If water in a stream or creek suddenly turns muddy or the amount of water flowing suddenly decreases or increases, this is a warning that the flow has been affected upstream. You should immediately leave the area because a debris flow may soon be coming downstream.
• Travel with extreme caution. Assume roads are not safe. Be alert when driving, especially at night. Embankments along roadsides may fail, sending rock and debris onto the road.