Stormwater runoff carries pollutants into Puget Sound. Using permeable pavement and smart landscaping protects water quality and salmon habitat.

Share story

Stormwater is the No. 1 source of pollution in Puget Sound – damaging water quality and harming aquatic life like salmon, shellfish and whales. When it rains, water from developed areas flows downstream, carrying with it pollutants like fertilizers, toxic metals, pesticides and sediment.

Low-impact development techniques like the use of permeable pavement can be used on a large scale by municipalities and industry to blunt the effects of stormwater. Boeing, Washington State University and the Washington Stormwater Center are partnering to research and develop durable, yet permeable pavement that allows water to slowly percolate into the ground But individual homeowners can play an important role in protecting water quality, too.

Here in the wet and wild Pacific Northwest, we can create rain gardens to help reduce stormwater originating from our gutters, patios, roofs, lawns, and driveways. Rain gardens naturally filter the stormwater and slow its flow before it enters freshwater lakes, rivers, streams and the Sound.

Similar to a native forest, rain gardens collect, absorb and filter stormwater runoff from areas that don’t allow water to soak into the ground. Understanding the right combination of soil, plants and location that allows water to soak in serve as the starting point for designing an effective rain garden that will:

  • Enhance the appearance of home and yards
  • Provide healthy habitat for insects and birds
  • Filter oil and grease from driveways
  • Reduce flooding on neighboring property, overflows in sewers and harmful erosion in streams.

Experts from WSU offer tips on creating a custom rain garden at home.

Anatomy of a rain garden

Rain gardens are usually just 12 to 14 inches deep. Water remains in a rain garden for one to two days at the most (not long enough for mosquitos to breed). A rain garden includes:

  • A dug depression that is flat on the bottom, with sloped sides
  • An inflow and overflow area (with piping and rock for overflow drainage)
  • A rain garden soil mix (if the existing soil will not suffice)
  • Plants selected for their ability to tolerate both wet and dry conditions (typically native plants)

Rain garden do’s and don’ts

  • Don’t install a rain garden over a septic tank, or in a septic drain field.
  • Do keep at least 50 feet between a rain garden and a septic system.
  • Do call to check the location of utilities before you begin to dig (800-424-5555).
  • Don’t plant in areas where water often puddles longer than 24 hours.
  • Do stay 10 feet away from building foundations.
  • Do stay at least 100 feet away from steep slopes or bluffs.

To learn more about how to create an effective rain garden, visit

Learn more about how Washington State University researchers untangle complex problems to enrich quality of life for us all.