Fortescue River

Vorlage:Infobox River 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 30km 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 westerly crossing the Great Northern Highway again North of the Auski Roadhouse. The river continues to head west crossing Highway 1 at the Fortescue Roadhouse and turns until discharging into the Indian Ocean at Mardie Station about 40km South West of Dampier

The river was named in 1861 during an expedition by the explorer and surveyor Francis Thomas Gregory who named it after CS Fortescue the Under Secretary of State for the colonies.

Tributaries

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 trubutaries also flooded. Weeli Wolli Creek and Weelumurra Creek both overflowed and caused floods and washaways on the Hamersley Iron and Mount Newman railway lines.

The river flows through a number of permanent water pools on the latter part of it's journey including; Tarda Pool, Mungowarra Pool, Crossing Pool and Deep Reach Pool.

Catchment

The Fortescue Catchment area drains from the southern side of the Chichester Plateau and the northern side of the Hamersley Range making use of the through between the two. The valley plains are composed of earthy clays with some cracking clays, loams and hard red soils.

Water is stored at Opthalmia Dam which holds a total volume of 32,000ML, and a total of 6,290 ML/year are drawn from the surface water for use in the town of Newman.

The catchment area at the headwaters of the river is particularly flat and marshy whre the Western Creek, Warrawanda Creek and Fortescue River converge, the river then flow through a poorly defined channel as far as Gregory Gorge when the river starts to form a well defined channel and flows through a number of pools before reaching the estuarine area.

Estuary

The mouth of the river is a large estuarine area. The estuary is mostly unmodified, and functions primarly as a result of river energy. The delta formed by the river is tide dominated. The estuary covers a total surface area of Vorlage:Convert The majority of the estuarine area is made up of saltmarsh and intertidal flats. A colony of mangroves use the estuary as habitat and occupy an area of Vorlage:Convert. Large female Barramundi are known to inhabit the estuary.