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Tips to Reduce Flooding

When it rains, street drains help to keep City neighborhoods from flooding. When leaves collect in gutters and block these drains, water can back up and cause ponding that slows or stops traffic and can even flood yards and homes. While autumn is when leaves are most likely to collect in drains, it can happen at any time of the year.

Our drainage crews work hard to maintain all of the City’s drainage infrastructure, including storm drains on streets. But with tens of thousands of drains spread all across the City, we need your help too. You can help prevent flooding by paying attention to what’s happening with the drains on your block. A few small maintenance actions on your property can also prevent stormwater from ponding.

Keep leaves and debris out of drains

  • Avoid piling yard waste like fallen leaves and sticks in your yard, where it could wash into City drains. Keep it in a yard waste bin or other container.
  • Use a rake or broom to remove leaves and debris from the tops of storm drains, and then place the material in your yard waste cart.
  • If the drain is still clogged after you’ve removed the debris, call our drainage problem hotline at (206) 386-1800 to report it.
  • If an inlet or street drain appears to be blocked by snow or debris, try to safely clear a channel to provide a path for the runoff. If the drain cannot be cleared, or if the cause of the blockage or flooding is uncertain, call Seattle Public Utilities at (206) 386-1800.

Maintain your gutters and downspouts

  • Clean the gutters and drainage downspouts attached to your roof twice a year. Just one wind or rainstorm can clog a well-flowing drainage system.
  • Inspect for leaks or damage to rain gutters that could cause a flat roof to flood.
  • Direct flows from downspouts away from your foundation, without discharging flows to adjacent properties.
  • Never discharge water over the edge of a steep hill.

Maintain your drainage systems

Maintaining the drainage system on private property is the owner's responsibility.

  • Check your property’s drainage system. This is especially important on commercial properties that have catch basins or other drainage systems. Maintaining these systems is the property owner's responsibility.
  • The best way to find out what’s in your pipes is to ask a professional to “video inspect” your underground drainage system.
  • If you have a driveway that leads down from the street, be sure to clear the drain at the bottom of the slope.
  • If you live at the base of a hill or on a cliff, ensure that drainage and retaining walls are properly functioning.

Respect the City’s drainage system

  • Don't put grass clippings, leaves or other debris into any of the drains, ditches, creeks, culverts, gutters or ravines in the City.
  • Do not store furniture or other items like firewood, fuel tanks, containers and loose items in your yard, as floodwaters can wash these items into culverts and cause flooding.
  • It is against the law to dump or to allow any material to enter the drainage system, as it leads to blockages. To report illegal dumping, call (206) 684-7587.

Assess your yard

  • Water is the most common cause of unstable slopes, mudslides and erosion. Check your property for signs of earth movement, such as leaning trees, or cracks in the soil or sidewalks. If you have a problem, contact a soils engineer (search the Internet for "Engineers-Geotechnical-Soils") to evaluate the situation.
  • Preventative planting can also help reduce the chance of a mudslide or flooding. However, avoid planting over side sewers that could create problems from plant roots in the future. For advice on which plants you could read Choosing the Right Plants.

Reduce runoff from your property that causes flooding

  • Collect water in rain barrels and cisterns. Learn more about rain water harvesting.
  • Create rain gardens. A rain garden acts like a native forest by collecting, absorbing, and filtering stormwater runoff from rooftops, driveways, patios, and other areas that don’t allow water to soak in. See the following list of resources including a manual for developing rain gardens (pdf). Contact the Garden Hotline for a hard copy at (206) 633-0224 or email help@gardenhotline.org.
  • Use permeable pavement in place of concrete or asphalt.
  • Grow a green roof. Green roofs extend the life of roofing materials by blocking ultraviolet radiation and moderating temperature extremes. They can also slow stormwater runoff, reduce building heating and cooling costs, cool and clean the air, and provide habitat and attractive greenery in urban environments.