ABSTRACT
Treatment wetlands in general are plant-soil-water systems utilized to promote water quality improvement. Some treatment marshes will be built on former wetland sites, putting them in a category of restoration projects. Treatment marshes often contain areas of open water, floating vegetation, and emergent plants; either by design or as an unavoidable consequence of the design configuration. Treatment marshes can be further classified according to vegetation growth forms, such as emergent macrophytes, submerged macrophytes, etc.; but in practice, marshes often contain more than one vegetation types found in different spatial distribution patterns. Modern municipal wastewater treatment plants produce better-than-secondary effluents. The amount of municipal effluent water that might be polished is usually small in comparison to agricultural runoff for the same watersheds. Urban runoff carries modest amounts of pollutants and is therefore a logical application for treatment marshes. The use of constructed wetlands, usually with accompanying ponds, is a routine best management practice for controlling the quality of runoff.
