Its catchment area is in the western Adelaide Hills, and it drains into Gulf St Vincent south of Glenelg.

[1] The catchment includes the Cowandilla-Mile End drainage network, the construction of which has replaced numerous small natural watercourses and swamp lands south of the Torrens River watershed.

[citation needed] This area includes the suburb of Brooklyn Park and the southern parts of Torrensville, Underdale and Lockleys as well as Cowandilla, Mile End and Adelaide Airport.

Damming, apart from enabling the Patawalonga to be navigable and thus a safe harbour for yachts and other recreational watercraft, was seen as a means of reducing or removing the odour from the estuary of the river.

It arises from seaweed that grows in the shallow depths of the river estuary and, in more recent times, due to stormwater pollution.

[10][11] An event like this occurred on the weekend of 22–23 January 2005; the front page of the Adelaide Advertiser reported that "Residents woke yesterday to an 'awful' stench and the sight of hundreds of seagulls converging on the area in a feeding frenzy.

"[12] From the 1970s onwards, increasing levels of rubbish and dirty stormwater would collect in front of the weir in the Patawalonga, bringing the stench and unsightly view of debris in the water at Glenelg North.

The Outlet's intention was primarily to enable dirty stormwater from the catchment to be diverted away from the Patawonga Lake at an ultimate cost of approximately A$30m.

Symbolically, the then Premier John Olsen took a media-attended swim in the Patawalonga as the State Government lifted the ban on recreational use.

[15][14] The Outlet project was initially dogged with controversy, due to failures to handle stormwater and pollution of Adelaide's beaches.

[19] Another failure in the Outlet in February 2003 resulted in minor flooding and consequent damage to homes in both Glenelg North and upstream Novar Gardens.

Heavy rainfall and a malfunction in the weir resulted in the Patawalonga breaking its banks at Glenelg North on Friday, 27 June 2003 and flooding the homes of local residents.

[21] The situation became a major political issue with the Premier, Mike Rann, declaring that he would establish a compensation fund for victims who had suffered water damage to their homes.

[22] 145 residents made 150 claims upon the fund and at least A$1.4m was paid to the victims, ultimately, by weir operator Baulderstone Hornibrook.