The "Eaton Hall—Mary—Hackett Lakes Wetland Complex" is a 259 hectare area on the Oak Ridges Moraine which represents the amalgamation of three previously defined wetlands: "Eaton Hall Wetlands", "Mary Lakes Wetlands" and "Laskay Wetlands". These constituent wetlands are each situated at the headwater area of the East Humber River watershed in King City. "The largest wetlands occur around seven kettle lakes, representing the best concentration of kettle lakes in any wetland complex on the Oak Ridges Moraine" Bounded by "Happy Valley Forest" to the west, the 225 wetlands in the complex "comprise one of the largest and most diverse wetland complexes on the Oak Ridges Moraine, noteworthy for its high concentration of significant plants, animals and kettle lakes."