Registered Professional Foresters (RPF) should address the following questions during Timber Harvesting Plan (THP) preparation. RPFs are encouraged to review California Division of Mines and Geology Note 50, Factors Affecting Landslides in Forested Terrain.
ü Are there unstable areas located within or adjacent to the proposed THP area?
ü If unstable areas were identified in the THP area, proposed timber operations on, adjacent to, upslope, or downslope of these features may have the potential to affect slope stability through:
Examples of timber operations that may produce these effects are:
ü If proposed timber operations have a reasonable potential to affect slope stability, and there is a potential for materials from landslides or unstable areas to affect public safety, water quality, fish habitat or other environmental resources, then a California licensed geologist with experience/expertise in slope stability should be consulted to assess slope stability and assist with designing mitigation measures.
A series of 7.5’ quadrangle landslide maps has been developed for use in THP preparation that covers much of the California Coast Range, from Monterey through Del Norte Counties. An index for these maps, California Division of Mines and Geology Special Publication 120, is available from:
Copies of the landslide maps are on file at the Division of Mines and Geology library at the above address and at the Department of Forestry and Fire Protection offices in Fortuna, Willits, Santa Rosa, and Felton.
Many of the maps that are published by the Division of Mines and Geology are available at:
www.consrv.ca.gov/dmg/index.htm