Blackwood River

Blackwood River
Colour Patch area at mouth of Blackwood river and start of eastern section of estuary
Origin	Junction of Arthur River and Balgarup River
Mouth	Hardy Inlet, Augusta
Basin countries	Australia
Length	300 kilometres (186 mi)
Source elevation	219 metres (719 ft)
Mouth elevation	sea level
Avg. discharge	29.8 m³/s
Basin area	28,100 square kilometres (10,849 sq mi)

Barrabup Pool, Blackwood River, near Nannup

The Blackwood River is a major river and catchment in the South West of Western Australia.

The river begins at the junction of Arthur River and Balgarup River near Quelarup and travels in a south westerly direction through the town of Bridgetown then through Nannup until it discharges into the Southern Ocean at Hardy Inlet near the town of Augusta.

The river has 41 tributaries including Dinninup Brook, Balingup Brook, St John Brook, Boyup Brook, Tweed River, Ti Tree Gully, Christmas Creek and Tanjannerup Creek.

The upper or larger catchment area of the river is in agricultural areas, while the middle catchment area passes through forest areas, and the lower portion of the river passes into mixed forest, agricultural and residential lands. The river emerges into Flinders Bay at Augusta.

It was discovered in 1827 by Captain James Stirling and named by Stirling after Vice-Admiral Sir Henry Blackwood, under whom he served as a Midshipman on HMS Warspite in 1808–1909 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.

Hardy Inlet has a number of islands – namely Molloy Island and Thomas Island.

The mouth of the river has attracted interest in its various points of opening and closing over the last 100 years, Duke Head at the west side being a benchmark location for the shifting mouth.

The river is prone to occasional flooding. In 1945 it rose to the highest level recorded to that date, running 1.1 metres (3.6 ft) 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 174 millimetres (6.85 in) 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 11.6 metres (38 ft), submerging over 50 houses in Nannup.

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. ISBN 1-920694-38-2
• 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 ISBN 1-920849-24-6
• 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. ISBN 0-7309-7450-2