Groundwater investigations - South West region

Details of our active and completed groundwater investigations in the South West region of Western Australia.
Map showing the locations of groundwater investigations in the South West region
South West groundwater investigations map

You can read about our investigations in the South West region below.

South West regional reconnaissance investigations

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In the South West region, groundwater supports drinking water, horticulture, pasture production and mining. The environment, recognised for its outstanding biodiversity and importance to the community, is also supported by groundwater. The Yarragadee, Leederville and Superficial aquifers are significant groundwater resources, and water levels in some areas are decreasing due to reduced rainfall and abstraction.

We investigated three high-priority areas in 2009 to improve our understanding of these resources:

  1. The Bunbury groundwater area (prompted by observations of increased salinity in the Yarragadee aquifer, which is the source of public water supply for Bunbury).
  2. The Busselton-Capel groundwater area (which has high levels of groundwater use for public water supply and irrigation).
  3. The Blackwood groundwater area (to investigate the potential of the Leederville and Lesueur Sandstone aquifers as regional groundwater resources).

The State Groundwater Investigation Program and the Australian Government’s Water Smart Australia program jointly funded these investigations.

What we did during the investigation

Through the South West regional reconnaissance investigation we:

  • installed one seawater interface monitoring bore at a near-coastal site in Bunbury (GSW1)
  • installed four groundwater monitoring bores into the Yarragadee aquifer in the Busselton-Capel area
  • installed five groundwater monitoring bores into the Leederville and Lesueur aquifers at two different sites in the Blackwood area
  • conducted geophysical logging in the deepest bores to help characterise aquifers
  • analysed samples for palynology to estimate geological age and improve our understanding of the stratigraphic relationships
  • installed groundwater dataloggers with six-hourly measurements to improve groundwater model calibration, resolve recharge responses, and understand aquifer connectivity.
Map of the reconnaissance groundwater investigation in the South West region of WA

Key findings and how we are using the information

In the Bunbury groundwater area, we made several key findings:

  • There is a mixing zone between fresh and saline groundwater between 45 and 75 metres below ground level, with saline water below 75 metres.
  • There is high vertical and horizontal permeability in the Yarragadee aquifer at the location of the monitoring bore.
  • Induction logging is a relatively simple and repeatable method of identifying the location of the seawater interface.

Installation of groundwater monitoring bores into the Yarragadee aquifer in the Busselton-Capel groundwater area improved the groundwater monitoring network and better defined the area’s geology and hydrogeology.

The investigation of the Leederville and Lesueur aquifers in the Blackwood groundwater area found that:

  • direct rainfall recharges the Leederville aquifer
  • the Leederville aquifer is not always present
  • the Lesueur aquifer has freshwater in the Rosa subarea.

We used our new understanding of aquifer parameters to improve our South West Aquifer Modelling System (SWAMS). Predictions from SWAMS helped revise the allocation limits for the South West groundwater areas allocation plan 2009. We will continue to monitor groundwater levels in these bores to evaluate the resources covered by the plan.

We used the investigation results to guide and optimise targeted investigations, including the South West groundwater areas, Royalties for Regions South West, and Statewide SWI investigations in the Bunbury and Busselton-Dunsborough areas.  

Where to get more details

You can download the South West groundwater areas allocation plan 2009.

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

  • Bore completion report for the South West regional reconnaissance investigations, HR287 (Denby 2009)
  • Hydrogeology related to the South West regional reconnaissance investigations, HR301 (Denby 2011).

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

Cowaramup groundwater investigation

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The Cowaramup area between Busselton and Margaret River is a popular tourist destination and wine-growing region. Aquifers became fully allocated in 1999. We investigated the groundwater resources in 2005–06 to improve our understanding of the area and help revise the volume of water available for sustainable, future use. We used the information from the investigation, combined with existing hydrogeological data, to develop a numerical groundwater flow model for the area and help make these decisions.

We increased the volume of groundwater available from the Leederville aquifer to 1.57 GL per year as a result of the investigation, helping to expand horticulture in this high-value area. We explain this increase in the South West groundwater areas allocation plan 2009.

This Cowaramup groundwater investigation was part of our flagship State Groundwater Investigation Program.

What we did during the investigation

Through the Cowaramup investigation we:

  • installed 14 groundwater monitoring bores to a maximum depth of 230 metres to improve our understanding of the hydrogeology and groundwater resources
  • collected water-level data from 61 bores at 27 locations
  • assessed the groundwater age, hydrochemistry and groundwater dependence of permanent pools along the Margaret River
  • built a subregional numerical groundwater model to help evaluate groundwater abstraction impacts and identify areas sensitive to water-level declines – such as groundwater-dependent ecosystems and neighbouring users.

Key findings and how we are using the information

The investigation identified that 1.5 billion litres of groundwater per year was available for abstraction for the high-water-demand Margaret River wine region. We estimated that this water was worth around $1.5 million each year for the wine industry.

Ongoing monitoring data from the bores installed during the study help us manage groundwater resources through allocation plans, plan evaluations and licensing.

Where to get more details

You can download the following publications:

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

  • Bore completion report for Cowaramup groundwater investigation, HR252 (Schafer 2006)
  • Cowaramup groundwater investigation, HR262 (Schafer, Johnson & Kern 2007)
  • Review of groundwater monitoring – Cowaramup investigation, HR270 (Tuffs 2008)
  • Groundwater resource assessment of the western Busselton-Capel groundwater area, HR273 (Schafer & Johnson 2009).

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

Scott coastal plain groundwater investigation

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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).

South West groundwater areas investigation

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Groundwater supports drinking water, horticulture, pasture production and mining in the state’s South West. It also supports the region’s highly valued environment and its outstanding biodiversity.

The South West groundwater areas investigation improved our understanding of how the environment connects to groundwater and expanded the monitoring network. We have used this information to secure water to support the local economy, while protecting the environment.

This South West groundwater areas investigation ran from 2008 to 2010, funded by the State Groundwater Investigation Program (SGIP) and the Australian Government’s Water Smart Australia program.

What we did during the investigation

Through this investigation we:

  • drilled 85 monitoring bores at 48 sites
  • analysed lithology, groundwater and acid sulfate soils potential
  • characterised ecosystems
  • collated existing hydrogeological data across the Swan and Scott coastal plains and the Blackwood Plateau.

Key findings and how we are using the information

We have:

  • improved our understanding of the extent and thickness of the Superficial aquifer
  • better defined the connection between the Superficial and Leederville aquifers between Dunsborough and the Capel River
  • improved our understanding of how groundwater supports the environment on the Swan and Scott coastal plains
  • updated acid sulfate soils risk maps by expanding our data across the Swan and Scott coastal plains and the Blackwood Plateau
  • expanded the groundwater monitoring network
  • improved the availability and quality of groundwater data for the existing bore network in our Water Information Reporting system.

We used this information to improve the South West Aquifer Modelling System model and support the South West groundwater areas allocation plan 2009. We continue to monitor the improved network and regularly evaluate the groundwater resources of the South West.

Where to get more details

You can download the South West groundwater areas allocation plan 2009.

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

  • Bore completion report: Swan coastal plain stratigraphic drilling program between Bunbury and Dunsborough, HR289 (Department of Water 2009)
  • Bore completion report: Groundwater-dependent ecosystems on the southern Swan coastal plain – interim report, HR293 (Wallace-Bell 2009)
  • Bore completion report: Scott coastal plain, HR296 (Chan 2011).

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

South West (Scott River) investigation

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Groundwater supports public drinking water supplies, horticulture, pasture production and mining in the vibrant South West region. Groundwater also supports the iconic Blackwood River system and the coastal wetlands that attract people to live in and visit the region. However, long-term groundwater availability is under threat from the combined pressures of high groundwater use and demand and a drying climate.

The four-year South West (Scott River) investigation has significantly improved our understanding of groundwater resources in the South West. It has helped to ensure the region has long-term water security for agriculture, industry and domestic purposes. It has provided further information to manage the risks of seawater intrusion and environmental impact from groundwater abstraction, while ensuring we better use the available water.

This groundwater investigation ran between 2012 and 2016 under the statewide Royalties for Regions Regional Water Availability program.

What we did during the investigation

We have:

  • collected almost 1,600 square kilometres of airborne electromagnetic (AEM), ground-based transient electromagnetic (TEM) and topographic data
  • completed isotope and chemistry sampling and analysis.
  • worked with expert scientists to study the connection between the Margaret, Capel, Blackwood, Donnelly and Warren rivers and the region’s major aquifers
  • developed a new South West Aquifer Modelling System (SWAMS), which supports groundwater management.

Key findings and how we are using the information

Through this project we:

  • located the boundary of the seawater interface within the three major aquifers in the region for the first time
  • calculated more precise recharge estimates considering rainfall, land use, depth to water and soil and geological conditions
  • confirmed groundwater supports flows in the Margaret, Capel, Blackwood, Donnelly and Warren rivers.

The investigation provided new information to improve the SWAMS model and informed the South west groundwater areas allocation plan 2009. We use the ongoing water monitoring data for regular evaluations of the groundwater resource.

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.

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).

Page reviewed 8 June 2022