Brown Hill, Keswick, Glen Osmond and Parklands Creeks are important drainage watercourses in metropolitan Adelaide.
Together, they drain a catchment area of 69 square kilometres extending from the Adelaide Hills in the east to Adelaide Airport in the west, with the combined catchment mainly contained within the local government areas of Adelaide, Burnside, Mitcham, Unley and West Torrens. This area is home to more than 200,000 residents.
Unfortunately, the creeks have a history of flooding and a low standard of flood protection, and therefore a relatively high flood risk.
To improve the standard of flood protection for homes, businesses and public facilities across the region, the five catchment councils of Adelaide, Burnside, Mitcham, Unley and West Torrens have collaborated to establish and implement the Brown Hill Keswick Creek Stormwater Project.
The Brown Hill Keswick Creek Stormwater Project
A number of catchment-wide flood mitigation studies have been undertaken in recent decades. However until the current project, attempts to finalise a flood mitigation plan had been largely unsuccessful. This included a study commissioned in 2003 by the then Patawalonga Catchment Water Management Board that led to a 2006 Master Plan.
In 2007, the Stormwater Management Authority was created under the Local Government (Stormwater Management) Amendment Act 2007, based on a Stormwater Management Agreement (SM) between the SA State Government and the Local Government Association.
Functions of the SMA were to include the facilitation and coordination of stormwater management planning by councils.
Current legislation concerning stormwater management and powers and responsibilities of various parties is contained in the Local Government (Stormwater Management Agreement) Amendment Act 2016 and the Natural Resources Management Act 2004.
As a result of the 2007 legislation, the five catchment councils assumed responsibility for implementing the 2006 Master Plan, thereby establishing the Brown Hill Keswick Creek Stormwater Project.
Under a Memorandum of Agreement between the councils, Unley Council acted as the host council in terms of providing for the administration and coordination of project-related matters, including entering into agreements with third parties.
In February 2008, the SMA conditionally approved the 2006 Master Plan as the Stormwater Management Plan for the catchment. However, due to subsequent concerns about aspects of the plan, the five catchment councils and SMA agreed in 2009 to prepare a revised SMP.
The revised SMP would comply with the Stormwater Management Planning Guidelines of the SMA (which were not introduced until 2007), including consideration of broader stormwater management initiatives, and in particular, stormwater harvesting and reuse.
Over subsequent years, extensive whole-of-catchment community consultation was undertaken on proposed flood mitigation measures to inform the development of the revised SMP.
In February 2017, the current SMP was approved and gazetted, which includes the construction of $140 million of flood mitigation infrastructure works along major watercourses of the catchment.
It is estimated that a one in 100-year flood would affect more than 2000 properties across the Brown Hill and Keswick Creek catchment and cause damages of about $122 million. Crucially, the SMP works are designed to mitigate the effects of such a flood to less than $1 million of damages on fewer than 100 properties.
Significantly, there are also other major benefits of the planned flood mitigation works, including creek rehabilitation, associated creek water quality and biodiversity improvements, as well as enhanced recreational amenity in open space areas traversed by watercourses. Works are also planned for improved quality of stormwater runoff and reduced impact on receiving waters.
Brown Hill and Keswick Creeks Stormwater Board
Following approval of the SMP by the SMA in 2017, the five catchment councils – under provisions of the Local Government Act – created a regional subsidiary in February 2018 to conduct the project.
Governed in accordance with a charter prepared by the councils and subsequently approved by the Minister for Local Government, the Brown Hill and Keswick Creeks Stormwater Board is now responsible for implementing the SMP, including the construction, management and ongoing maintenance of flood mitigation works.
The five members of the board, who are independent of the constituent councils, were selected through the process of a nominations committee comprising one representative of each council. The board now acts on behalf of the councils, who retain overall responsibility for the SMP.
For more information about the Brown Hill Keswick Creek Stormwater Project, visit bhkcstormwater.com.au