Agricultural Drainage Wells (ADWs)--also known as shallow injection or dry wells--have been used in some farming situations as a way to carry excess water from surface or subsurface drainage systems directly into deeper layers of the ground. ADWs threaten groundwater quality because they allow agricultural runoff and the pollutants it may contain to feed directly into the groundwater. Normally, natural filtering of runoff takes place as water seeps slowly through several layers of fine-and medium-textured soil before it reaches the groundwater. This natural filtering is bypassed when an ADW is used, potentially polluting the groundwater.
www.wca-infonet.org
