Flooding & Erosion

Flooding Information

Flooding at Percival LandingIf you witness localized flooding BEFORE it becomes an emergency call Olympia Public Works at 360.753.8333 - Option 0.

If your home is flooding, or if flooding is causing a public safety hazard call 9-1-1 

Stay away from power lines and electrical wires, electrical currents can travel through water. Report downed lines and power outages to PSE at 1.888.225.5773.

In Your Home

  • Never use gasoline-powered pumps or generators indoors to pump out basements as they produce deadly carbon monoxide exhaust fumes.
  • Raise items that could be damaged up off the floor in areas prone to flooding such as basements.
  • Ensure your electronic equipment are unplugged and up off the floor.

On the Road

  • DO NOT drive through flooded areas. If you see a flooded road ahead, turn around. Find another route to your destination.
  • DO NOT drive around barricades - they are there for your safety.
  • If you must drive through water, drive slowly and steadily. Be aware that six inches of water will reach the bottom of most passenger cars, causing loss of control or possible stalling.
  • If your vehicle stalls in the deep water, be aware that restarting may cause irreparable damage to the engine.
  • If you have driven through water up to the wheel rims or higher, test your brakes on a clear patch of road at low speed. If they are wet and not stopping the vehicle as they should, dry them by pressing gently on the brake pedal with your left foot while maintaining speed with your right foot.

If Using Sandbags

  • Place them in the direction of the water flow with no space in between.
  • Stagger the second row on top of the first (similar to the way that bricks are staggered in a wall). This system provides added protection.
  • Limit your stack to three layers of sandbags, since any more may not be sturdy.
  • After flooding is over, Never use the sand from sandbags to fill children's sandboxes or playgrounds, as it is not high-quality sand and the sandbags may have been contaminated.
  • Never dispose of sand in a wetland, flood plain, waterway or any other sensitive area.

Visit the Emergency Management Division's FloodSafe website for more flood safety tips, including how to prevent home flooding and what to do after a flood.


You Can Help Prevent Flooding - Rake a Drain

If minor flooding occurs, use a garden rake or shovel and remove the leaves and other debris from the storm drain and dispose of them.

YOUR SAFETY COMES FIRST! If you feel it is unsafe, or flooding is severe, contact Olympia Public Works dispatch for assistance at 360.753.8333 - Option 0.


Erosion - Steep Slopes

Hillside erosion at Percival CreekEvery winter, rainfall saturation causes some slopes in Olympia to fail. Sometimes there is only slight movement, other times an entire section of the slope slides downhill.

  • 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.

If your slope is in danger it is important to take steps throughout the year to protect and stabilize it. Slope failure can be minimized by managing your stormwater, establishing deep-rooted vegetation and removing excess weight.

Download our "Homeowners Guide to Protecting Your Slopes" for detailed instructions.

Erosion Questions? Contact Eric Christensen at 360.570.3741 or echriste@ci.olympia.wa.us


Steep Slopes are Highly Regulated

Steep slopes are considered critical areas and are coverd by City tree removal and landslide hazard ordinances. These ordinances do not prevent you from working on your slope, but do help ensure that the work is done correctly to minimize slope failure and damage.

Download our "Homeowners Guide to Protecting Your Slopes" for more information.