What is Green Stormwater Infrastructure?

The problem is daunting, but we know an effective solution: green stormwater infrastructure. 

Low-impact development (LID) is the best alternative to development that otherwise sends untreated stormwater runoff directly into waterways like Puget Sound. LID strategies—such as incorporating green roofs, permeable pavements, and rain gardens into new development—use or mimic natural processes to collect and filter stormwater runoff before it can reach our waterways. LID manages the flow of stormwater and filters out pollutants, protecting people, water quality and aquatic habitat from pollution. LID also provides urban flood protection and cleaner air, and can increase property values, community aesthetics, and local recreation opportunities.

Stormwater retrofits add treatment (to filter out pollutants) or controls (that slow the flow of stormwater to ensure treatment or prevent flooding) to existing development. LID is required for new development and new construction in our region. Retrofitting, on the other hand, requires tearing up existing pavement and installing stormwater controls or installing new stormwater treatment or flow control facilities. These projects can address areas that were developed before current stormwater regulations required LID for new development.

We all have a role to play in treating and controlling polluted stormwater runoff. Individual residents and homeowners, commercial and industrial property owners, developers, municipalities, and the Washington State Department of Transportation can all implement green stormwater infrastructure in their communities or encourage more widespread adoption. But our cities and counties control some of the largest infrastructure components in our region and can have an outsized impact.

Rain gardens slow and absorb stormwater, helping to prevent it from running across impervious surfaces and into our waterways. Photo courtesy Rain Dog Designs, via The Seattle Times.

Developers throughout the Puget Sound region are currently required to treat and control stormwater pollution by incorporating green stormwater infrastructure and using other Low Impact Development techniques (LID) as they build. However, there are far fewer requirements to control stormwater from existing development. This is problematic in older urban areas, where hard surfaces can cover more than 90% of the land. These areas need to be retrofitted to better control stormwater