during the Napoleonic Wars, in the North Sea and the Mediterranean. Historically it was of considerable importance in the early days of the Swan River Colony, and more recently of importance in the ecology of the Augusta-Margaret River region due to conflicts in land use policy. The upper catchment contains Toolibin Lake, a nature reserve and Ramsar site. The river is prone to occasional flooding. In 1945 it rose to the highest level recorded to that date, running over the Russell Street bridge in Nannup. The river flooded again in 1946 and 1947 closing roads but not causing any significant damage to towns along the river. In 1949 Nannup received of rain in a period of seven hours, causing flooding. A bridge over the Blackwood connecting the town to Busselton was swept away. In 1982 after the remnants of a tropical cyclone passed through the southwest, the town and surrounding areas were inundated by heavy rains. The Blackwood rose , submerging over 50 houses in Nannup. References Further reading Brearley, Anne, Ernest Hodgkin's Swanland : estuaries and coastal lagoons of South-western Australia Crawley, W.A. : University of Western Australia Press for the Ernest Hodgkin Trust for Estuary Education and Research and National Trust of Australia (WA), 2005. Muirden, Peter: Pen, Luke and Marnie Leybourne (2003) Stream and catchment hydrology in South West Western Australia Perth, W.A. Dept. of Environment. Department of Environment river restoration, 1442-6919 ; report no. RR19 Pen, Luke J.(1999) Managing our rivers : a guide to the nature and management of the streams of south-west Western Australia (editor, June Hutchison) East Perth, W.A. : Water and Rivers Commission. Rivers of the South West region Warren bioregion