Heavy rain is forecasted this weekend across the Northern Oregon Cascades and the Greater Portland Metropolitan Area, which may result in river flooding, flooding in small streams and urban areas, and debris flows across burned areas in the Cascades. This encompasses areas burned earlier this year by the Riverside fire in Clackamas County, including the Highway 224 corridor between Estacada and Ripplebrook.
Debris and mud flows are rivers of rock, earth and other debris saturated with water. They can flow rapidly, striking with little or no warning at avalanche speeds — faster than you can run. They also can travel many miles from their source, growing in size as they pick up trees, boulders, cars and other materials. Debris flows don’t always stay in stream channels, and they can flow sideways as well as downhill.
Listen and watch for rushing water, mud, unusual sounds and movement
- Unusual sounds, such as trees cracking or boulders knocking together, might indicate moving debris.
- A faint rumbling sound that increases in volume is noticeable as the landslide nears.
- Fences, retaining walls, utility poles, k-rails, boulders or trees move.
During a landslide or debris flow
- Heed all warnings and evacuation notices.
- Never cross a road with water or mud flowing.
- Never cross a bridge if you see a flow approaching; it can grow faster and larger too quickly for you to escape.
- If you do get stuck in the path of a landslide, move uphill as quickly as possible.
- Avoid river valleys and low-lying areas during times of danger.
- If you are near a stream or channel, be alert for any sudden increase or decrease in water flow or for water that changes from clear to muddy. These can be signs that a landslide or debris flow is coming.
After a landslide or debris flow
- Stay away from the slide area. There may be danger of additional slides.
- Listen to local radio or television stations for the latest emergency information.
- Watch for flooding. Floods sometimes follow landslides and debris flows because they may both be started by the same conditions.
- Check for injured and trapped persons near the slide, without entering the direct slide area. Direct rescuers to their locations.
- Allow trained professionals to check the building foundation, chimney, and surrounding land for damage.