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 6 . The increase in bedload and woody debris delivery to coastal streams from landsliding is probably the most important factor in creating stream channel change following logging. Increased landslide rates are attributed to many factors.
Road building disrupts subsurface drainage, often creating points of water concentration.
Road sidecast can overload and oversteepen already steep slopes. Soil strength is reduced by the decay of anchoring roots in the years following tree harvesting. Yarding operations can disrupt natural drainage pathways and can create new ones, and can result in gullies infilled with woody slash, increasing the potential for or magnitude of debris torrents. There are three landslide-related issues to be considered. The first issue is the potential for slides to occur in a particular area.