A wastewater treatment system for deployment in a body of water having a floor and a water surface includes an in-pond clarifier extending across the body of water. The in-pond clarifier defines a clarifying chamber and includes an upper portion and a lower portion. The upper portion is suspended above the wastewater surface. The lower portion is maintained adjacent to the floor of the body of water. As a result, the body of water is divided into distinct treatment zones on opposite sides of the clarifying chamber. The in-pond clarifier further includes a plurality of pumps for removing biological solids which settle within the clarifying chamber. Separate pumps are provided for either returning settled solids to the body of water or for wasting settled solids from the body of water.