<p>Wetlands are complex ecosystems that have improved water quality by processes inherent to the system. There are varied criteria used to establish the existence of a wetland.</p> <p> During the last 20 years interest in the use of wetlands for wastewater treatment has increased. Natural and constructed wetlands were reviewed related to their ability to treat agricultural and domestic wastewaters, stormwater run-off, and acid mine drainage. Currently operating natural and constructed wetland treatment systems were reviewed using raw data and published articles. Treatment efficiencies related to nutrient and metals removal varied with the wetland configuration, climate, and types of wastewater treated.</p> / Master of Science