Stormwater management - Southwest Washington

Treatment wetland





Treatment wetland

A stormwater treatment wetland is a shallow man-made pond designed to treat stormwater through the biological processes associated with aquatic plants. These facilities use dense wetland vegetation and settling to filter sediment and oily materials out of stormwater.

Wetlands take advantage of nature's approach to removing pollutants. They also provide habitat for amphibians, aquatic insects and birds. Vegetation occasionally may be harvested and sediment removed, primarily to maintain the original storage capacity of the wetland. In general, stormwater wetlands do a good job of removing sediment, metals and pollutants.

Treatment wetlands need to be maintained to stormwater facility standards to avoid redesignation as a natural wetland, where permits are required for maintenance work. 

Signs that maintenance is needed and a checklist for maintaining the facility including how to fix problems.