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Project Background

What is stormwater and why is it a problem?​

A car driving through a large pudde in a fooded road
A close up of a stormwater drain with dirty water flowing from the street into the drain
A group of 3 Orca whales swimming in the ouget soundwith the Downtown Seattle skyline in the background

Stormwater is water that comes from precipitation and snowmelt. In developed areas such as Seattle, we have many hard surfaces such as roadways and rooftops that do not allow stormwater to soak into the ground. Flooding can occur when a lot of stormwater runs over hard surfaces.

The runoff from rain also picks up fertilizers, pesticides, soaps, and other pollutants from the ground. It transports them to the nearest storm drain and local waterways, contaminating water quality and harming fish and other wildlife.

The City of Seattle is working to reduce the amount of polluted stormwater runoff flowing into Thornton Creek and Lake Washington. 

Natural Drainage Systems (NDS)

Natural Drainage Systems (NDS) hold and clean polluted stormwater, removing pollutants before they reach Thornton Creek. NDS offer multiple benefits to local neighborhoods and ecosystems, including:

  • Increased landscaping

  • Lower risk of flooding

  • Creation of habitat along our streets

  • Healthier creek ecosystems

  • Traffic calming

  • More street trees

  • Pedestrian safety improvements


NDS installations include spongy soil and deep-rooted plants that clean and filter toxins in water.


How a typical NDS planting installation changes over time: 


The Thornton Creek community is interested in...

  • Addressing drainage and flooding issues in Northeast Seattle

  • Improving water quality in the neighborhood

  • Reinforcing the public right-of-way in the project area

  • Roadway parking changes

  • Pedestrian safety

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