After a fire many trees are weakened from burning around the base of the trunk. The trees can fall over or blow down without warning. Shallow-rooted trees can also fall. Therefore be extremely alert when around burned trees.
NOTE: Please DO NOT attempt to remove burned trees before consultation with appropriate parties. Even severely damaged tress may recover, or may provide valuable habitat if left standing. Removal of dead trees may be hazardous.
Intense rainfall post-fire can create significant debris flow due to vegetation loss and soil exposure. These flows are a major risk to life and property because they can occur with little warning, can exert great impulsive loads on objects in their path, and may strip vegetation, block drainage ways, and damage infrastructure. Cases of sudden and deadly debris flows are well documented along the Western United States.
After an intense wildfire, burned vegetation and charred soil form a water repellent layer, blocking absorption of water and increasing runoff. Upcoming rain events may induce flash flooding and mud flows, both of which are a significant threat to life and property. Flooding can be a hazard even if the property is not mapped as a high-risk flood area.
There is an increased threat of rock fall in some areas because of damage to vegetation and shallow rocky soils and slopes in affected watersheds. Debris barriers and rock fall netting can be effective in capturing smaller rocks but larger rocks will require more substantial measures. If there is a threat of large rocks releasing from slopes on your property or adjacent properties then seek professional assistance. Contact the USDA Natural Resources Conservation Service (NRCS) or local Resource Conservation District (RCD).
Roads and driveways are significantly impacted by forest fires and if left unchecked may lead to debris flows and flooding. Corrugated plastic culverts are often melted completely away and roadside ditches may be filled with debris. A thorough inspection of any road networks on the property should be conducted. For issues with roads in the Public Right of Way, please contact the Napa County Public Works – Roads Department.