Scott coastal plain groundwater investigation

We investigated the Scott coastal plain as part of our State Groundwater Investigation Program

Between Augusta and Pemberton on the Scott coastal plain, irrigation, stock watering and mineral sand mining rely on groundwater. Groundwater supports cultural and environmental features, including Lake Jasper (the largest freshwater lake in south-western Australia) and wetlands in the D'Entrecasteaux National Park. Increased groundwater abstraction puts the health of these culturally and environmentally significant features at risk.

The investigation improved our understanding of the connection between the Yarragadee and Superficial aquifers and their groundwater-dependent values. We used the new information to build a predictive groundwater model (the South West Aquifer Modelling System – commonly referred to as SWAMS) to support groundwater resource management in the area. The results from SWAMS helped develop the South West groundwater areas allocation plan 2009. As part of the investigation, we also constructed a groundwater monitoring network to allow us to evaluate and manage the system over time.

The Scott coastal plain groundwater investigation was undertaken in 2005–06 as part of the our flagship State Groundwater Investigation Program.

What we did during the investigation

Through the Scott coastal plain investigation we:

  • installed a total of 13 groundwater monitoring bores at five sites, up to 40 metres depth into the Yarragadee and shallower aquifers
  • collected samples to analyse palynology (pollen grains and other spores) to determine the geological formations present
  • analysed groundwater samples for major ions and nitrates
  • monitored groundwater levels in new bores monthly for two years.

We evaluated the performance of the resource using data from bores installed during the investigation in a groundwater resource review, which we completed in 2008.

Key findings and how we are using the information

The Scott coastal plain investigation improved our knowledge of the local geology and hydrogeology by better defining the extent of the Superficial, Leederville and Yarragadee formations. The investigation found:

  • the Leederville Formation outcrops in the north
  • the Superficial and Yarragadee aquifers are connected closer to the coast, where the Leederville aquifer is absent
  • the hydrogeology represented in the SWAMS is suitable for the long-term sustainable management of the Scott coastal plain.

We used this information to develop the South West groundwater areas allocation plan 2009. We continue to monitor these bores and regularly evaluate the groundwater resources.

Where to get more details

You can download the following:

You can ask for copies of the internal technical reports for this investigation by emailing groundwater.info@dwer.wa.gov.au. These include:

  • Scott coastal plain drilling project proposal, HR243 (Lindsay 2005)
  • Bore completion report for eastern Scott coastal plain groundwater investigation, HR253 (Irwin 2006)
  • Hydrogeology of the eastern Scott coastal plain, HR257 (Irwin 2006)
  • Review of groundwater monitoring, Scott coastal plain, HR271 (Tuffs 2008).

Go to our Water Information Reporting portal to access data from the monitoring bores installed during the investigation.

You can access all government-commissioned airborne geophysical surveys via the Department of Mines, Industry Regulation and Safety website and download them free of charge from ‘Geophysical Surveys’ in GeoVIEW.WA or from the Geophysical Archive Data Delivery System (GADDS).

Read more about our groundwater investigations by region across Western Australia.

Page reviewed 8 August 2022