Water and Wastewater Terms Beginning O

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

overturn

The almost spontaneous mixing of all layers of water in a reservoir or lake when the water temperature becomes similar from top to bottom. This may occur in the fall/winter when the surface waters cool to the same temperature as the bottom waters and also in the spring when the surface waters warm after the ice melts. This is also called turnover.