State Groundwater Investigation Program

The Department of Water is currently investigating Western Australia’s groundwater resources, with actions planned through to 2020. A sound knowledge of groundwater resources and monitoring of changes are essential for effective planning to ensure sustainable management of the State’s water resources.

The program is improving our scientific understanding of the sustainability of groundwater systems throughout the State. Full details are in our publication Investigating Western Australia’s Groundwater Resources – A 15 year plan of action.

The program’s timing is driven by the large increase in groundwater use over the last decade and a large projected growth in demand. It is linked to the licensing of groundwater users.

The investigation program will bring social, economic and environmental benefits for Western Australia. Already it is giving us:

• a better understanding of the distribution and quality of groundwater resources;
• information to better support, encourage and enhance mining, industrial, agricultural and regional development; and
• new data to improve water resource management under changing climate conditions.

The focus is in areas of increased groundwater usage, where currently we do not have enough information to assess groundwater resources and ensure sustainable management.

Although the purpose for each investigation may be slightly different, the common objectives are to:

• define the size and extent of aquifers;
• understand groundwater salinity distribution;
• determine the sustainability of the groundwater resources in order to manage impacts and use; and
• improve the monitoring of groundwater levels and groundwater quality in the long-term.

The program began in July 2005. For the first three years, the focus is on the metropolitan area and horticultural districts, such as Cowaramup and Gingin, in the Perth Basin (see map).

From the fourth year onward, more regional groundwater investigations will be introduced progressively to provide a balanced, State-wide assessment. The program is helping the local area committees that advise on local groundwater resources management policy, and private self-supply users who wish to establish groundwater supplies.

Our staff are responsible for supervising contractors, data analysis, interpretation and report writing. All information from the program is being made available in printed reports and distributed via the Internet.

Map of investigation areas

Program updates

March 2008

There has been increased progress on the Gnangara North investigation with 12 surface casings installed at six sites. The groundwater model for Cowaramup has been reconstructed with a draft report still in progress. A first draft of the entire Southern Perth Basin bulletin will be presented before June 2008. Air-core drilling for the Gingin Brook investigation will commence in 2008/09. Planning is well advanced for stratigraphic coring at three sites in the South West and Gnangara, in support of the Water Smart Australia. A seismic geophysical survey is being planned for Allanooka and Gnangara North, in conjunction with Curtin University's Geophysics Department.

Program updates

December 2007

Cable tool drilling is still continuing at Gnangara North to install surface casings. There have been delays on the Cowaramup assessment with poor calibration of the numerical groundwater model. There is excellent progress on the Southern Perth Basin bulletin by Pennington Scott, and as such they have been engaged to produce the Northern Perth Basin bulletin. The Gingin Brook investigation is planned with a drilling tender in the market place. The Dongara Line and Kalgoorlie Palaeochannel reports were published in October 2007.

September 2007

Progress on the Gnangara North investigation has been delayed due to poor ground conditions with lost circulation. A cable tool contractor has been employed to install surface casing to recommence mud-rotary drilling in mid 2008. There has been great progress on the writing of the Southern Perth Basin bulletin with a first draft of the geology chapter. The Gingin Brook investigation is largely planned with a final assessment and drilling proposal.

June 2007

The drilling of the Gnangara North investigation has commenced but there are delays due to poor ground conditions with lost circulation. There has been substantial progress on the Cowaramup assessment using PETREL. Work has commenced on the Southern Perth Basin bulletin. There has been planning for the Gingin Brook investigation with an assessment and drilling proposal nearly finalised. A final draft of the Dongara investigation report is being peer reviewed.

March 2007

The Eastern Scott Coastal Plain report was published in February 2007. A contract has been awarded to Pennington Scott to compile the Southern Perth Basin bulletin. Results from the airborne geophysical survey at Allanooka are being interpreted. There were no respondents to the drilling tender for the Gnangara North investigation that was released in March 2007. A report on the Cowaramup investigation is in first draft and will be used in the construction of a groundwater model.

Program updates

December 2006

Bore completion reports have been finalised for all investigations from 2005/06. The Eastern Scott Coastal Plain report is in its final draft. Work has commenced on developing a contract specification for the Southern Perth Basin bulletin. A contract has been awarded to Fugro Airborne for an airborne geophysical survey at Allanooka in December or January 2007. Planning of the Gnangara North investigation is well advanced with permissions and approvals finalised and drilling contracts being developed.

September 2006

Bore completion reports have been finalised for the Cowaramup and Scott Coastal Plain investigations.

The bore completion report for the Gingin-Cowalla investigation is nearly finalised with minor delays due to difficulties in accessing a surveying contractor. There has been significant progress on the groundwater resource assessments at Cowaramup and Scott Coastal Plain with the latter to be published by December 2006.

In 2006-07, groundwater investigations will focus in two prime areas: Casuarina and Gingin Brook. The Yarragadee Aquifer at Casuarina (50km east of Geraldton) will be investigated and assessed for potential water supplies for the expanding horticulture and mining industries.

The new investigations will be important for improving understanding about groundwater resources in this poorly-understood part of the Northern Perth Basin, which will support regional development and protect Geraldton’s town water supply at Allanooka. The investigations may involve using airborne geophysical techniques for site selection and installing deep monitoring bores to 300 metres.

Gingin Brook is an iconic and unique water feature in Western Australia with perennial river flow related to discharge from the Mirrabooka and Leederville Aquifers in its headwaters. Increasing pressures on Gingin Brook from groundwater and surface water abstraction has driven the investigations to better understand groundwater contribution to baseflow and assess the potential impacts of abstraction. This investigation will involve the drilling and installation of multiple piezometers at 12 sites along Gingin Brook.

June 2006

There has been substantial progress on the implementation and operation of the State Groundwater Investigation Program. The Minister for Water Resources (Hon John Kobelke) launched the State Groundwater Investigation Program at Cowaramup on 24 February 2006. The program is now fully underway with three drilling investigations completed during 2005-06.

The Cowaramup groundwater investigation comprised seven drill sites with 14 new monitoring bores installed. The drilling was undertaken between January and May 2006. Though further assessment is required and is continuing, it would appear that there are potential new groundwater resources in the Cowaramup area.

Ten monitoring bore sites were completed in the Gingin-Cowalla area to better monitor impacts from local groundwater abstraction. The drilling operations were undertaken between April and June 2006.

During April 2006, investigations were also completed within the Scott Coastal Plain involving the installation of 13 new monitoring bores at five different sites.

Now that the three investigations are finalised, all data will be interpreted and assessed before the results are communicated to all stakeholders by the end of the 2006.

There has also been progress on the planning and gaining permissions for the Gnangara North and Allanooka Yarragadee investigations. Planning has also begun on an investigation of the Lower Gingin Brook to understand groundwater conditions, surface water/groundwater interactions and determine potential impacts from local groundwater abstraction.

Commencement of State Groundwater Investigation Program,
9 January 2006

Mud-rotary drilling rig operating at Scott Coastal Plain

Hydrogeologist (Rochelle Irwin) examining drill sample.

Cable-tool drilling rig operating along Cowalla Road in Gingin

Completed monitoring bores at Cowaramup