Blackwood River

Source of the Blackwood River

The Blackwood River has its named source at the confluence of the Arthur and Balgarup Rivers, forty kilometres north-east of the township of Boyup Brook. This is about 400 kilometres from the mouth at Hardy Inlet, Augusta.

Hydrologically, however, the watercourse termed the Arthur River is the same as the Blackwood. The Arthur River is termed as such from its confluence with the Yilliminning River in a salt lake system in the Arthur River Nature Reserve about 30 kilometres northwards of Wagin.

From this point, however, the watercourse has many inputs, including the Yilliminning. The Yilliminning’s source is about eight kilometres south-west of Wickepin.

The Yilliminning flows about 34 kilometres south to its junction with the Arthur in the Nature Reserve. The Arthur flows about 140 kilometes generally south-west to its junction with the Balgarup River about 11 kilometres south-south-west of Moodiarrup from which point the two watercourses are named the Blackwood River.

Naming of the Blackwood River

The Blackwood was named by Governor James Stirling in May 1830 after Vice Admiral Sir Henry Blackwood under whom Stirling had served during his early Royal Navy career. The Arthur River was named by Stirling on 30 October 1835 during the Great Southern Expedition. It was named after Mr Arthur Trimmer, a member of the expedition. The name for the Yilliminning River is of unknown aboriginal derivation, first recorded by Surveyor J.O.Oxley in 1892

The first Europeans to explore the Blackwood River were a small party under the command of Thomas Turner. They set out from the settlement at Augusta in 1834 and travelled as far as where Nannup is now. It was to be eight years before further exploration occurred. Surveyor Augustus Gregory (after whom Mt Augustus is named ) explored the upper reaches in 1845 and later carried out the first survey of the Blackwood Valley. The first settlers followed soon after.

Catchment

This Upper Catchment includes Lake Dumbleyung and local streams tend to drain into this area. Unless the lake overflows the Upper Catchment does not contribute to the flow of the Blackwood River. The Blackwood River catchment covers an area of approximately 22,000 square kilometres and is the largest catchment in the South West of Western Australia. This catchment covers an area slightly larger than Israel. The greater part of the Blackwood Catchment is to east of the Darling Scarp.

Flow

The annual average discharge of the Blackwood River is 620 million cubic metres – about 1.8 times that of the Avon-Swan system. And although it is the longest river with the largest flow in the South West it is puny by comparison with the mighty Ord River in the Kimberley. That river’s average annual flow is 4,300 million cubic metres. During one particularly wet year it discharged 12,500 million cubic metres into the ocean. This enormous quantity of water is the equivalent of all the divertible surface and groundwater resources of the whole State in an average year. 

Environmental

The Blackwood River faces environmental problems common to many areas of Australia, including a rising ground water table associated with salinity, water logging and increased risk of flooding, erosion, loss of biodiversity and declining channel conditions.

The Blackwood Basin Group (BBG) was established in 1992 in response to growing community concerns about the declining health of the river and catchment.

Length of the Blackwood River

FROM TO KMS ACC
Glenorchy Bridge Ualling Crossing 15 15
Ualling Crossing Trigwell Bridge 13 28
Trigwell Bridge Hicks Road 13 41
Hicks Road Condinup Bridge 21 62
Condinup Bridge Boyup Brook 16 78
Boyup Brook Upper Blackwood Bridge 18 96
Upper Blackwood Bridge Mandalup 11 107
Mandalup Winnejup Bridge 16 123
Winnejup Bridge Winnejup Falls 3 126
Winnejup Falls Sunnyside 14 140
Sunnyside Bridgetown 12 152
Bridgetown Rocky Bluff 9 161
Rocky Bluff Maranup 25 186
Maranup Southampton 10 196
Southampton Wrights Bridge 14 210
Wrights Bridge Maidments 12 222
Maidments Dudinalup 7 229
Dudinalup Nannup 15 244
Nannup Jalbarragup 29 273
Jalbarragup Darradup 9 282
Darradup Milyeannup 8 290
Milyeannup Laymans Flat 19 309
Laymans Flat Punch Road 10 319
Punch Road Sues Bridge 17 336
Sues Bridge Warner Glen Bridge 27 363
Warner Glen Bridge Alexander Bridge 13 376
Alexander Bridge Molloy Caravan Park 13 389
Molloy Caravan Park Augusta 10 399

 Expeditions on the upper Blackwood River

Blackwood Source Expedition 1997

Blackwood Source Expedition 1994

Upper Blackwood Expedition ’92

REFERENCES

Epton, Kim, Rivers of the Kimberley, Hesperian Press, 2000.
De Silva, Smith, Rutherford and Ye, Hydrogeology of the Blackwood River Catchment Western Australia.
Sir James Stirling’s journal, J.S. Roe F.B. 10. Exp Plan 124a. Joanne Shoobert, principal ed., Western Australian Exploration, vol. 1, Hesperian Press, Perth, 2005, pp.451 & 468.

 

 

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