A catchment is an area of land that drains to a single point or outlet. Catchments are generally named after the main river that carries runoff water to its outlet. Because water always runs downhill, ridgelines separate one catchment from another. You can find ridgelines, and hence the catchment boundaries, by following each stream or drainage line upstream to the hill where it starts, then draw a line between the hills.
Hunter’s Hill Local Government Area is split between two main catchments, the Lane Cove River catchment and the Parramatta River catchment. Clarke’s Point at Woolwich indicates where the mouths of the river estuaries meet and flow into Sydney Harbour with the ridgeline, separating the catchments running through the middle of the Hunter’s Hill Council area. Hunter’s Hill Council is committed to improving the quality of water that flows to receiving environments and is working with other councils to maintain and improve the environmental value of these catchments.