After a fire, there is a risk of post-fire flash flooding and debris flows. These natural disasters can happen in the years following a major wildfire and should be considered in local hazard mitigation planning. A mudslide took place near Dodson, OR, in January 2021, which was one of the areas in the Columbia River Gorge where the terrain had been destabilized. The trees that provided structural integrity to the steep hillsides were burnt away, leaving large areas of the Gorge more susceptible to debris flows, even years after the fire.
Following the Eagle Creek Fire, the Oregon Department of Transportation (ODOT), the Oregon Department of Geology and Mineral Industries (DOGAMI), and the U.S. Geological Survey (USGS) collaborated to create a post-fire landslide response plan. They also worked together on a hazard map to address potential post-fire debris flow and flood emergencies. Officials in the communities throughout the Gorge who were affected by the Eagle Creek Fires are prepared to react to these hazards with clear plans and visuals to help direct disaster response.
In Clackamas County, Oregon, local officials were concerned about the Sandy River's propensity for flooding and the subsequent bank erosion, which was undermining roads and structures in stretches along the river. As a result of the erosion threat, property owners adjacent to the river had begun to stabilize and fortify the banks. However, the impact and effectiveness of these efforts along the bank were unknown.
FEMA and the Oregon Department of Geology and Mineral Industries (DOGAMI) launched a cooperative study of a stretch of the Sandy River in the summer of 2012. The study used Light Detection and Ranging (LiDAR) and previously available bridge data in order to produce a Limited Detailed Study (LDS) to guide plans for the 2013 building season. Through this cooperative Risk MAP effort, Clackamas County received valuable information on both the short term (velocity) and long term (channel migration) behavior of the Sandy River for use in mitigation and planning needs.