The landslide hazard for most of Mason County is “Extreme”. The Washington Department of Natural Resources (DNR) has a beta version of a website called “Shallow Landslide Hazard Forecast Map” which is an interactive map that shows the landslide hazards around the State. When you click on Mason County, the map has a pop-up window that says, “Landslide hazard is EXTREME and landslide initiation is expected to be very frequent and widespread”
The website is based on “antecedent rainfall, 24-hour, and 48-hour predicted rainfall.” This landslide hazard information is produced in a partnership between the Washington State Department of Natural Resources—Division of Geology and Earth Resources and NOAA—National Weather Service.
The site does have a disclaimer since it is still under construction: “The data on this site cannot be used to predict definitely that landslides will or will not occur; it is intended to show the relative hazard of occurrence. Landslides may occur in counties that have a low hazard rating and may not occur in all or any areas at high hazard.”