Posted in Web Slough (hydrology) – Wikipedia May 1, 2020 A slough (/ s l uː / (listen) or / s l aʊ / (listen)) is a wetland, usually a swamp or shallow lake, often a backwater to a larger body of water. Water tends to be stagnant or may flow slowly on a seasonal basis. https://en.wikipedia.org/wiki/Slough_(hydrology)