The Great Lakes-St. Lawrence River Basin Sustainable Water Resources Agreement was signed in 2005 by eight US states and two Canadian provinces, to regulate and promote co-operation as regards diversions and water withdrawals in this vast and complex hydrological system. In Australia, the federal government has no competency to manage rivers under the Constitution, but has recently been referred powers by the state governments to assume some responsibilities for the Murray-Darling River basin (Box 4.20).