Stormwater Wetlands

Stormwater wetlands are wetland areas used for the treatment, transportation and storage of large volumes of stormwater runoff. They are typically constructed, human-made wetlands created for the purpose of managing stormwater runoff.

However, existing wetlands may sometimes be preserved or restored to provide a stormwater management function. But careful consideration must be given to ensure the use of an existing wetland for this purpose is compatible with the wetland’s natural characteristics.


  • A reduction in runoff volume.
  • Improved treatment, transportation and storage of stormwater runoff.
  • Enhanced wildlife habitats.
  • An increase in the aesthetic value of yards and neighborhoods.

Design Considerations:

  • Must be functional, maintainable and attractive to ensure long-term success.
  • Are ideal as additions to existing facilities.
  • Requires long-term maintenance and monitoring to ensure success of wetland ecological features.
  • Variations include pocket, shallow marsh, extended detention and pond-type wetlands, all of which are best suited for specific sites. Additional research is necessary before their installation.
  • Choosing the proper landscaping and planting plan is critical to the performance of a stormwater wetland.
  • Landscaping-on-the-Edge
  • Professional assistance from experienced wetland biologists may be required to ensure effectiveness and prevent wildlife disturbances, aesthetic depregation and mosquito infestations.

See the Retrofit Considerations page for guidance when integrating stormwater wetlands with an existing water management system.


Manmade wetlands 

Manmade wetlands are very effective in filtering out pollutants from stormwater, and they also provide valuable habitat for wildlife. Courtesy of  Nevue Ngan Associates

wetlands can be designed to retain a large amount of water 

Wetlands can be designed to retain large amounts of water, thereby reducing flooding. Courtesy of Carla Palmer