Green Streets are an alternative to conventional street drainage systems designed to more closely mimic the natural hydrology of a particular site by infiltrating all or a portion of local rainfall events. A green street uses trees, landscaping, and related environmental site design features to capture and filter stormwater runoff within the right of way, while cooling and enhancing the appearance of the street.
Stormwater runoff from impervious surfaces, including urban streets and roads is a major threat to water quality in the Washington region. Urban roads, along with sidewalks and parking lots, are estimated to constitute almost two-thirds of the total impervious surface cover and contribute a similar ratio of stormwater runoff.
On December 18, 2012, the Anacostia Watershed Restoration Partnership requested that the TPB develop and approve a regional policy on Green Streets, similar to the regional policy on Complete Streets. At the direction of the TPB Technical Committee, a stakeholder workshop was held on April 8th, 2013 to review current Green Streets policies and practices. Workshop participants concluded that Green Streets are often the most cost-effective response to stormwater runoff regulations, and that a directive from the top of a government can help ensure that various agencies within a government will cooperate to implement Green Streets.
Department of Transportation Planning and Department of Environmental Programs staff then developed Green Streets Policy, Guidance, and Resources documents with input from the TPB Technical Committee and other stakeholders.
On February 19, 2014 the TPB approved Resolution R10-2014 that endorsed the concept of Green Streets and strongly encouraged its member jurisdictions and agencies that do not already have a Green Streets policy, or who are revising an existing policy, to adopt a Green Streets policy that includes common elements that the TPB believes reflect current best practices.