Oregon Department of Forestry (ODF) officials have closed a dispersed camping site along Ben Smith Creek in the Tillamook State Forest due to a landslide creating the potential for flooded trails and camping sites.
The landslide encompasses approximately 18 acres and has deposited trees and sediment into the stream. The debris from the landslide has caused a change in the course of the stream and also created the potential for large amount of material to move downstream in a debris flow. During heavy rainfall and high flows, sediment is moving from the slide area through Ben Smith Creek and into the Wilson River.
Ben Smith Creek enters the Wilson River just above where Oregon Highway 6 crosses the Wilson at Lee's Camp, about 25 miles east of Tillamook. ODF geotechnical specialists have determined that any additional release of material at the landslide location does not pose a risk to motorists using Highway 6 nor pose a hazard to homes located on the Wilson River.
Some recreation trails surrounding Ben Smith Creek (accessed from Hwy 6 on Ben Smith Road) have been closed by ODF until further notice due to the potential for trail washouts and debris flows. Signs have been posted by ODF at trailheads to advise members of the public about the safety concerns. Large sections of wood will continue to end up in the creek, creating new habitat for fish as a result.
ODF geotechnical and engineering specialists began reviewing the area in 2010 and determined the release of debris at the creek is part of a larger hillside failure in a landscape where slide activity is part of the natural erosion process. The landslide is considered slow-moving, having been identified as a concern by ODF geotechnical specialists in November 2010. The first activity in the landslide area occurred prior to 1994-95 when it was discovered by ODF personnel preparing for thinning operations and road rebuilding.
"These actions are part of a natural process always at work in NW Oregon forests," said Mike Buren, ODF geotechnical specialist. "These changes are going on in the forest undetected by most people, especially in fall and winter."
Specialists from ODF will continue to monitor the landslide area throughout the winter and spring of 2012.
Additional photo and video resources about the landslide incident are available on the ODF web site: www.oregon.gov/ODF/newsroom/newsreleases/2011/NR1175.shtml