Sustained wet weather on steep slopes can make soils unstable, causing a landslide. In remote areas, the impacts of landslides are minimal, but when they occur near homes and roads, the results can be devastating. On one hand, landslides are a natural geological event that occurs on rain-drenched hillsides. On the other, human activities such as timber harvests can exacerbate the risk.
In 1996, following a couple of drenching storms in western Oregon that resulted in thousands of landslides, a change was made to the state’s forest practices rules to reduce the risk of timber harvests causing destructive landslides. The rule change gave the Oregon Department of Forestry the authority to prohibit a timber harvest on steep slopes when homes or busy roads lie in the path of a potential landslide.
Another major rule change dates back to 1983. It prohibits a crude type of forest road construction that was prone to landslides. The Oregon Department of Forestry has found that roads built since this rule was established are less likely to experience a landslide.
The Department of Forestry can suggest or require forest landowners to leave trees near some smaller stream channels after a timber harvest; if a landslide occurs, the trees are carried downstream. Large chunks of wood and logs in streams improve fish habitat, meaning slides can be ecologically beneficial in the long term.