Landslides indicate unstable terrain.
The frequency of occurrence of landslides within a watershed is an indication of the presence of potentially unstable slopes. Forest development activities, particularly the construction of roads, can reduce slope stability and initiate slope failures. Impacts from a slide into a stream can range from minor water quality degradation to the initiation of a major debris torrent. The effects of sediment contributions to surface water are discussed in detail in Appendix 9 . The increase in bedload and woody debris delivery to streams from mass wasting is probably the most important factor in creating stream channel change following logging.