About the Catchment Area : Creeks & Rivers

The Onkaparinga River
The river begins near Mount Torrens in the Mount Lofty Ranges, at around 650 m elevation, and flows south westerly to the river’s mouth at Port Noarlunga. The catchment area for this magnificent river is approximately 564 km2 and consists of a number of tributaries including, Aldgate Creek, Cox Creek, Lenswood Creek, Inverbrackie Creek, Aldgate Creek, Echunga Creek and the Kongorilla Creek

Overtime the river has created some of the State’s most picturesque scenery - the Onkaparinga Gorge nestled in the Onkaparinga Hills is just one example.

History and human impact
The Onkaparinga river as we refer to it today has in its past had many variations in spelling and pronunciation.

The river was first discovered by Europeans in 1831. Captain Collet Barker came across it while searching for an outlet to Lake Alexandrina. He recorded the name of the river as Ponkeurringa Creek, as given to him by the local indigenous people. A few years later, in a plan of the area, known as Arrowsmiths 1841 Plan, the river was called Unkaparinga.

Around the same time a Dr Wyatt, who was reported to be the Protector of Aborigines, spelt it Ungkeperringga and gave its meaning as ‘Mother river; plentiful’. Finally it was the wish of Governor Gawler to keep the indigenous names of localities, so later the river was given its proper designation Onkaparinga. Its true meaning is derived from ‘Ngangki-parri-unga, The Place of the Woman’s River’

Today the Onkaparinga River is a major source of drinking water for Adelaide and over the years, the catchment has been highly modified for the purposes of harvesting the water.

Landowners too have impacted on the river with properties adjoining it also diverting water from the river for household use, irrigation, animal husbandry and industrial uses.
Flow.

Water quantity
The rainfall reaching the river varies considerably along its length with 1100mm per annum falling in the upper part of the catchment, down to around 400mm per annum of the coast.

Before European settlement, the Onkaparinga River was ephemeral, that is the river did not flow all-year round. During summer, dry streambeds separated large pools.
Today, the hydrology of the Onkaparinga River catchment is influenced by the operation of the Metropolitan Adelaide Water Supply System.

River Murray water is pumped into the Onkaparinga River at Hahndorf where it flows to the Mount Bold Reservoir. Water is then released from Mount Bold Reservoir to be diverted via Clarendon Weir to the Happy Valley Reservoir where it is treated and filtered before being supplied to Adelaide for consumption.

Surface water within the catchment is not a prescribed resource and therefore there are no requirements for a licence to extract water or measure water usage.

The Onkaparinga Catchment Water Management Board is undertaking a study to determine how much flow the Onkaparinga should have to meet the needs of the environment.

Water quality
Instances of poor water quality in the Onkaparinga River are caused by a number of factors including pesticide and fertilizer run off from agricultural activities and stormwater pollution in populated and industrial areas. The discharge of water from wastewater treatment plants and malfunction septic systems also contribute to the poor quality of water flowing in the river.

Salinity levels in the river are highly variable with the lowest levels recorded in winter when most flow comes from surface run-off, to high levels in summer when the main component of flow comes from groundwater, which naturally contains more minerals than most surface run-off.

Photo Library
Click on the images below to view a larger image. These images are copyright to the Onkaparinga Catchment Water Management Board - April 2004.

More information
Click here to read more about the Board's vision of giving more water back to the Onkaparinga River.