December 2007 Storms in the Pacific Northwest

In December 2007, a series of snow, wind and rainstorms battered western Oregon and Washington, causing severe flooding and wind damage. Landslides occurred, roads and bridges were washed out, and homes were flooded.

The storm renewed interest in whether harvesting on steep slopes exacerbates landslides and flooding, and whether existing regulations that govern such harvesting are adequate.

A small portion of Weyerhaeuser timberland that received extraordinarily high rainfall suffered hundreds of landslides. We responded with a comprehensive research study designed to inform and improve forest management, and evaluate the relationship between our harvesting practices and landslides. The preliminary study results clearly indicate that the unusual intensity of the storm was the primary factor responsible for the large number of landslides. This work incorporates an extensive U.S. Forest Service study (2008), which concludes that harvesting practices have little impact on flooding in large storm events.

The study should be complete in late 2009. In the interim, we are taking steps to improve the way we conduct technical assessments for determining landslide risk associated with harvesting.