The Patawalonga Creek was once connected to the Torrens River and Port River through the reed bed system bounded on the west by a wall of sand dunes and to the east wetlands.
The Patawalonga Catchment covers 235 square km and takes in parts of the City of Adelaide, the eastern, western and southern suburbs and a portion of the southern Adelaide Hills. There are six sub catchments or surface drainage systems; two in the City of Unley being Brown Hill Creek and Keswick Creek.
Brown Hill Creek drains an area approximately 36 square km. The creek rises near Stirling in steep country which, although not urbanised, has been largely cleared. The rural catchment contains Brown Hill Creek Recreation Park. Within the urban area, the catchment is defined by council drainage systems. In Unley, Brown Hill Creek has retained a natural flow path and has a number of linear parks along its banks and for significant lengths is in private property.
Keswick Creek drains approximately 31 square km and has two main tributaries, Glen Osmond and Parklands Creeks, both of which contain some rural catchment. The catchment of Glen Osmond Creek includes a significant part of the South Eastern Freeway while the Parklands Creek drains part of the southern section of the City of Adelaide.
In Unley, Glen Osmond and Parklands Creek are both highly engineered and in many reaches have been confined to concrete culverts for flood mitigation purposes.