<Tr> <Td_colspan="2"> Website: NSW Environment and Heritage webpage </Td> </Tr> <P> The Hawkesbury River (also Hawkesbury - Nepean River), is a semi--mature tide dominated drowned valley estuary located to the west and north of Sydney, New South Wales, Australia . The Hawkesbury River and its associated main tributary, the Nepean River, virtually encircle the metropolitan region of Sydney . </P> <P> The Hawkesbury River has its origin at the confluence of the Nepean River and the Grose River, to the north of Penrith and travels for approximately 120 kilometres (75 mi) in a north--easterly and then south--easterly direction to its mouth at Broken Bay, about 15 kilometres (9.3 mi) from the Tasman Sea . The Hawkesbury River is the main tributary of Broken Bay . Secondary tributaries include Brisbane Water and Pittwater, that together with the Hawkesbury River flow into the Tasman Sea at Barrenjoey Head . </P> <P> The total catchment area of the river is approximately 21,624 square kilometres (8,349 sq mi) and the area is generally administered by the Hawkesbury--Nepean Catchment Management Authority . </P>

Where does the hawkesbury river start and end
find me the text answering this question