Is Your Home or Property Susceptible to a Landslide?
Northwest Clackamas County is more susceptible to landslides than many other locations in the Portland-Metro area. Slides are commonly triggered by heavy rain, rapid snow melt, earthquakes, grading/removing material from bottom of slope or adding loads to the top of the slope, or concentrating water onto a slope (for example, from landscape irrigation, roof downspouts, or broken water/sewer lines). Slides generally occur on moderate to steep slopes, especially in weak soil.
The City of Oregon City has a digital mapping program; once there, you can access the City's GIS mapping program, OCWebMaps, which includes Oregon City and outlying areas. In the Map Layers list, there is a section labeled “Hazards and Flood Info”, which contains information for steep slopes and landslide areas (please note that to view a layer, you must check the box beside it, AND check the box beside the “Hazards and Flood Info” section). Essentially, you can navigate to your address and see if your residence is in any of the known hazardous areas.
My Home is Located within a Hazards Zone; what are My Options Now?
Oregon City regulates and limits tree removal, grading and development in areas with steep slopes or historic landslides. More information is available by going to the Planning Division page or by calling them at 503.722.3789. They can answer questions related to development in areas within the Geologic Hazard Overlay zone; more information can be found in Chapter 17.44 of the Oregon City Municipal Code.
Activities in the hazard zones identified in OCMC 17.44.025 require that a Geologic Hazards Checklist be completed.
Additional Resources and Information
Another fantastic source to learn more about landslides and how to prepare for them is at the Oregon Department of Geology. This site also has digital mapping programs showing historical landslide information for all of Oregon. A handy Homeowner's Guide to Landslides booklet has also been published by the Department of Geology at Portland State University in cooperation with the Federal Emergency Management Agency (FEMA).
If you determine you might be at risk of a landslide, you might consider contacting your insurance company to find out about obtaining landslide insurance.