Controlling sediment and erosion will reduce the negative environmental impact of sedimentation on our rivers and watercourses, as well as reducing the financial burden of drainage maintenance on local governments.

The Southern River Water Quality Improvement Plan was developed in 2009 by the (then) Swan River Trust with the assistance of the Cities of Gosnells and Armadale. The Plan identifies, amongst other issues affecting water quality in the Southern River catchment, that the impact of sediment and erosion on the Southern River and its tributaries is a significant issue.

Erosion of soil from development and housing construction sites results in sediment entering the stormwater system. Depending on the location and design of the stormwater network, this results in negative impacts on the stormwater management infrastructure and/or the Southern River and its tributaries. Poor site management results in:

  • An unnecessary and not insignificant cost to local government to remove sediment from the stormwater management network.
  • An unacceptable negative environmental impact on important waterways.

The problem is apparent across the Perth metropolitan area. Perth Region NRM has taken a lead in convening  the Sediment Task Force to assist local governments, state government agencies and industry stakeholders to develop tools to manage the issue.

A detailed study through the University of WA and the Cooperative Research Centre for Water Sensitive Cities will help understand the magnitude and impact of sedimentation and assist in determining further action by regulators and stakeholders in sediment management.

The study is sponsored by the Cities of Gosnells, Armadale and Kwinana, Perth Region NRM, the Western Australian Local Government Association, the Department of Parks and Wildlife, the Water Corporation and Main Roads WA, and will focus on the developing areas of the Cities of Gosnells, Armadale and Kwinana.