Image Credit: Native Plant Solutions, 2018
Photograph Image Credit: Native Plant Solutions, 2018

Subsurface Gravel Wetland

A subsurface gravel wetland is a system containing both a subsurface gravel bed and a surface marsh. Stormwater runoff is infiltrated through the marsh into the gravel bed. The gravel bed filters pollutants and conveys water to an outlet structure.


  • The NJDEP recommends allowing wetlands plants to establish prior to system operation.
  • Liners may be necessary if soil conditions do not meet the degree of impermeability required by the NJDEP.

Cost: Subsurface gravel wetlands are generally more expensive than constructed wetlands per square foot. The gravel layer and piping requires additional excavation.
Maintenance: Subsurface gravel wetlands are similar to constructed wetlands. However, additional measures to maintain water levels and to inspect clogged piping are necessary. Subsurface gravel wetlands require regular inspection, maintenance of water levels, debris/sediment removal, and landscape services for vegetative areas.

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