Steep Slopes - Erosion

Is your slope eroding or hazardous? Every winter some slopes fail in Olympia when conditions cause the soil to move downhill. Sometimes there is only slight movement, other times an entire section of the slope slides downhill. Winter is the typical season for slopes to move because of rainfall saturating the slope. The rest of the year is the time to manage your slope to best protect your property.

Is Your Slope in Danger?

Steep slopes with grades of over 40% are most vulnerable to failure.

• Moderate slopes with grades over 10% can fail when impacted by features such as impervious soil layers, springs, seeping groundwater, or past movement.
• Slopes with only low-growing, shallow-rooted vegetation are more likely to slump, collapse, or slide when rainfall or other water saturates the ground.

Slope Failure can be Minimized:

• Manage your stormwater;
• Establish deep-rooted vegetation; and
• Removing excess weight.

Fact Sheet Available:

Review or download our attached "Homeowner's Guide to Protecting Your Slopes"  and learn more about protecting and stabilizing your slopes.

DVD Available:

For a free DVD on Managing Your Steep Slope with presentations by Ben Alexander of Sound Native Plants; Susan Messegee, Senior Planner, City of Olympia; Craig Tosomeen, Engineer, City of Olympia; and Steve Wise, Code Enforcement Officer, City of Olympia, contact Patricia Pyle at 360.570.5841 or email publicworks@ci.olympia.wa.us.

Steep Sloping and Erosion Questions:

If you have additional questions, please email publicworks@ci.olympia.wa.us, or call Eric Christensen at 360.570.3741.

Contact Information:

•   Street flooding emergencies: Public Works emergency dispatch for assistance at 360.753.8333, Option 0.
• Ongoing Stormwater or erosion-related problems: Environmental Code Enforcement at 360.753.8346. 24-hour messaging available.
• Property flooding: For localized or nuisance flooding, call Environmental Code Enforcement at 360.753.8346. 24-hour messaging available.
• Visit our Olympia City Services page for links to other services and contact information (phone numbers). 
• Contact us at publicworks@ci.olympia.wa.us

Other Resources:

• General Emergency Preparedness Information.
• Thurston County Emergency Management Alerts/Announcements