 It comprises an extensive (c. ) floodplain of the lower Murrumbidgee River and its tributaries, including the confluence of the Murrumbidgee with the Lachlan River, with numerous swamps and lakes.The extent of the floodplain has been reduced in size from over at the beginning of the 20th century by the construction of dams, irrigation systems and other hydraulic engineering works, with the water inflow declining by at least 60% between 1888 and 1998.Apart from Yanga National Park (established in 2005 on the former Yanga Station) most of the floodplain consists of commercial irrigated farmland.