The Phillips River is an ephemeral

Ephemeral

Ephemeral things are transitory, existing only briefly. Typically the term is used to describe objects found in nature, although it can describe a wide range of things....

 river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in the Goldfields-Esperance region of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

.

The headwaters of the river rise on the sanplains below Mount Madden and flow in a southerly direction, crossing the South Coast Highway approximately 20 kilometres (12 mi) West of Ravensthorpe

Ravensthorpe, Western Australia

Ravensthorpe is a town 541 km south east of Perth, 40 km inland from the south coast of Western Australia. It is the seat of government of the Shire of Ravensthorpe...

 then entering the Fitzgerald River National Park

Fitzgerald River National Park

Fitzgerald River National Park is a national park in Western Australia , southeast of Perth, in the Shire of Ravensthorpe and the Shire of Jerramungup....

 then veering eastward to follow a fault-line in the Quartzite

Quartzite

Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...

 rocks around the Eastern end of the Barren Range. The river finally discharges into Culham Inlet

Culham Inlet

Culham Inlet is an inlet located in the Goldfields-Esperance region of Western Australia. The inlet is also referred to as a coastal salt lake or a transient estuary, as the sand bar that prevents it discharging is almost always closed...

 and, when the inlet is open to the ocean, into the Southern Ocean

Southern Ocean

The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...

.

The river has six tributaries

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 including; West River, Jackilup Creek, Yarracarrup Creek and Kybalup Creek.

The rivers catchment is 35% cleared, with the southern half lying within the boundaries of the Fitzgerald River National Park

Fitzgerald River National Park

Fitzgerald River National Park is a national park in Western Australia , southeast of Perth, in the Shire of Ravensthorpe and the Shire of Jerramungup....

. The entire catchment lies within the Fitzgerald River Biosphere.
The river only flows for a short time during the year, mostly during the winter months. The river water is naturally saline but varies from almost fresh to more saline then seawater.

Named by John Septimus Roe

John Septimus Roe

John Septimus Roe was the first Surveyor-General of Western Australia. He was a renowned explorer, and a Member of Western Australia's Legislative and Executive Councils for nearly 40 years.-Early life:...

, who was the first European to discover the river in 1848. The river is named after his son in law, Samuel Pole Phillips.