UNDO-ing stormwater in WA!

UNSO screenshot

There have been many exciting developments afoot recently in Western Australia’s Department of Water.

The first of which was the official launch of the Department’s UNDO tool: Urban Nutrient Decision Outcomes. The tool was officially launched yesterday at the UDIA Luncheon by the Minister for Water, Mia Davies.

The web-based tool allows users to undertake a conceptual decision process that evaluates nutrient reduction decisions for urban developments.  It has been specifically tailored to  model developments on the sandy Swan Coastal Plain in south-west Western Australia.

Users have the ability to test a range of structural or non-structural design options to evaluate and reduce nutrients exported from their proposed urban development. It is designed to be easily used by development/their consultants (like us!), and for assessment by local and state government authorities.

In summary, relevant parties can use the UNDO tool as part of the land use planning process to:

  • determine the nutrient impacts of an urban development in a consistent manner that is supported by local, national and international scientific literature;
  • enter data and information about the development to assess its nutrient export in a logical and easy-to-use system;
  • allow land development proponents to design and put forward various management practices that would reduce the nutrient impacts of the development (and adhere to targets if targets are outlined for the development area);
  • report and summarise the development design, the proposed nutrient management practices and the nutrient exports clearly and concisely; and
  • allow assessment by state and local government agencies to streamline the approval process in a consistent manner.

Given that there hasn’t been a model specific for WA conditions (while east coasters have had the MUSIC model available to them for over a decade) to allow us to understand the effects of developments on the Perth environment, this is a truly exciting……development!

To access the latest version (1.1) please head to the Department of Water’s website:



In addition to developing a fancy new tool, the Department has also just released an updated version of its Decision Process for Stormwater Management in WA: Draft for Consultation.

The document was originally conceived to outline the State government’s approaches and criteria for planning and designing new and existing (retrofitting) stormwater systems throughout Western Australia.  The purpose being to encourage the inclusion of urban stormwater systems which help to transform Perth into a water sensitive city, with water sensitive communities.

This third edition of the document is a part of the Department of Water‘s Stormwater Management Manual for Western Australia.  This update was developed to:

  • apply current best practice international approaches and criteria for small rainfall event management;
  • review requirements for the north-west and north of Western Australia when applying the 1-year, 1-hour average recurrence interval rainfall event criterion to avoid over-sized systems;
  • consider shallow groundwater management at the beginning of the stormwater management decision process;
  • strengthen the case for small rainfall event management to be considered early in the design of urban stormwater management systems;
  • incorporate the new rainfall event terminologies from Engineers Australia’s review of Australian Rainfall and Runoff;
  • explain how to include natural hydrological processes in stormwater management
  • provide an explanation of stormwater management relating to management of receiving water bodies and their buffers;
  • consider urban liveability and amenity in the design of stormwater and shallow groundwater management systems; and
  • provide updated information on stormwater management in the land and water planning process.

The Decision Process provides clear guidance for planning and design of urban stormwater systems that:

  • protect public health and safety;
  • protect public and private infrastructure and buildings from flooding;
  • protect and enhance sensitive receiving environments by managing the water cycle, water quality, habitat diversity and biodiversity;
  • enable economically sustainable construction, maintenance and renewal/replacement costs; and
  • achieve good urban amenity.

Your comments on this document are very welcome so if you’re keen to put your two cents in, the closing date for submissions is 21 October 2016.

Submissions can be mailed/emailed to:

Department of Water Attn: Emma Monk, Urban Water Branch PO Box K822 Perth WA 6842