Fortescue River

Fortescue River
Ophthalmia Dam, Fortescue River
Country	Australia
Basin features
Main source	Ophthalmia Range 602 metres (1,975 ft)
River mouth	Indian Ocean
Basin size	49,759 square kilometres (19,212 sq mi)
Physical characteristics
Length	760 kilometres (472 mi)
Discharge	Average rate: 391 GL/a (12.4 m3/s; 438 cu ft/s) (mean)

The Fortescue River is an ephemeral river in the Pilbara region of Western Australia. It is the third longest river in the state.

The river rises near Deadman Hill in the Ophthalmia Range about 30 km south of Newman. The river flows in a northerly direction parallel with the Great Northern Highway until it crosses the highway just south of the Marble Bar turn-off. The river then runs north-west then west crossing the Great Northern Highway again, north of the Auski Roadhouse. Approximately 100 kilometres (62 mi) north of Newman, the river flows through the 960 square kilometres (371 sq mi) Fortescue Marsh, an important wetland. The river continues to head west crossing Highway 1 at the Fortescue Roadhouse (21°17′44.32″S 116°08′17.52″E / 21.2956444°S 116.1382000°E / -21.2956444; 116.1382000) and discharges into the Indian Ocean at Mardie Station about 40 km south-west of Dampier

The river is known to have 24 tributaries that include: Western Creek, Warrawanda Creek, Shovelanna Creek, Kalgan Creek, Fortescue River South, Cowcumba Creek, Macklin Creek and Tanga Tanga Creek.

During Cyclone Joan in 1975 many of these tributaries also flooded. Weeli Wolli Creek and Weelumurra Creek both overflowed and caused floods and washaways on the Hamersley Iron and Mount Newman railway lines.