Future water source planning in Great Southern Region

The LGSTWSS supplies drinking water to Albany, Mount Barker, Kendenup and Narrikup and Denmark (as required) from local groundwater sources on the South Coast and from surface water from Angove River near Two Peoples Bay, east of Albany. 

We continue to respond proactively to the ongoing challenges of climate change by investigating potential new water sources for the LGSTWSS.

These include:

• new groundwater sources;
• local seawater desalination.

As part of an investigation into a groundwater source option, we looked at the Manypeaks and Angove areas. These appear to be the most suitable areas from a hydrogeological point of view and are close to existing water infrastructure. 

Several locations in Princess Royal Harbour and Frenchman Bay, including the Vancouver Peninsula, have been investigated for seawater intake to supply a possible seawater desalination plant.  Frenchman Bay and on the South Coast have been investigated for discharge of brine, known as outfall. 

Findings from our investigations have identified that some of the options are no longer feasible. This means that we are not progressing:

•    groundwater at Angove (near Two Peoples Bay) 
•    desalination intake in Princess Royal Harbour 
•    desalination outfall at South Coast  

We also looked at Vancouver Peninsula and Salmon Holes, however, investigations were discontinued due to high cultural values. 

Frenchman Bay is still being considered for desalination intake and outfall infrastructure. Further investigations will help us assess whether the site is suitable.

The Big Grove, Little Grove and Goode Beach areas are being investigated as possible pipeline routes and wherever possible we would use road reserves or Crown land to minimise impacts on private landowners and the environment. We initially proposed the seawater desalination plant to be co-located at our existing South Coast Groundwater Treatment Plant site in Torndirrup. Stakeholder engagement has since identified opportunities for potential plant locations closer to the Frenchman Bay area, which we will also investigate.

Before we determine the location of a preferred water source, we consider the following factors at a minimum: 
water quality

• drying climate patterns and rainfall / streamflow data
• environmental considerations, including impact of drawing water on local ecosystems and construction impacts on existing flora and fauna habitats
• heritage and Native Title rights
• community feedback
• impact on private landowners
• water treatment requirements
• amount of water we expect to draw from the source and;
• cost of supplying water to our customers including building the required infrastructure.

Though Denmark is now connected to the Lower Great Southern Towns Water Supply Scheme (LGSTWSS), water will only be sent there if required, such as if there are a few dry years resulting in a demand shortfall in Denmark. 

We are still in the early stages with a decision on preferred option/s expected in 2025, following a detailed review of data and results.

We will engage with DWER, other government agencies, stakeholders and the community before making decisions on future sources for the LGSTWSS. 

Water Corporation is working with the Department of Water and Environmental Regulation (DWER) as we investigate long-term supply options. DWER is developing the Albany and hinterlands water allocation plan for public comment. It covers how groundwater and surface water will be managed and regulated in this area. The plan sets limits about how much water can be used and how much is left in the aquifer for the environment.

Water Corporation also continues to liaise with the Department of Primary Industries and Regional Development (DPIRD) about a potential seawater desalination plant.  DPIRD is working with the Minister for Fisheries to confirm the Albany Aquaculture Development Zone. The final stages include licences and tenure within the Princess Royal Harbour and King George Sound areas.

The Torndirrup National Park cliffs are a barrier between the Southern Ocean and Albany; they are over 170m high in some places. The energy required to pump seawater from the South Coast over the cliffs does not make this a viable option at this time.

We encourage residents to install rainwater tanks in regions with reliable annual rainfall patterns such as the South West and Great Southern regions. Though the efficiencies gained from collecting rainwater are valuable, they don’t close the gap between supply and demand, particularly in a changing climate where rainfall is increasingly less reliable. Rainwater tanks are also more expensive than other options when compared on a per kilolitre basis, which is why we encourage home owners to collect rainwater for household use if this is their personal preference and we offer financial incentives to help. We run a number of Waterwise offers such as showerhead swaps and rebates for rainwater tanks to help customers achieve this, and to reduce the cost difference. The rebates on rainwater tanks are only available in the Great Southern and South West regions due to the more reliable annual rainfall patterns. Visit our Waterwise Towns webpage for further information about offers relevant to your area each year.

Local Government is responsible for the operation approvals and installation of greywater systems in Western Australia. The West Australian Greywater Guide provides further information on how to best reuse domestic greywater in Western Australia

Seawater desalination works by separating water molecules from the seawater stream. First, seawater is passed through initial screening and pre-treatment to remove bigger particles like seaweed and sand. The seawater stream is then forwarded to the reverse osmosis membranes, water molecules pass through the membranes while the seawater passes on by, becoming saltier. Freshwater is produced (about 40% of the volume), along with saltier seawater (or brine, about 60% of the volume).  Brine is about twice the saltiness of seawater – it contains the original amount of salt but with less water.  

Brine is returned to the ocean through a pipeline with a diffuser at the end. The diffuser is designed to maximise the mixing and dilution of the brine. Mixing and dilution back to natural seawater salinity levels typically occurs within tens of metres from the diffuser. By completing brine dispersion modelling using information on local waves, tides and water currents, we are able to see how the brine would mix and disperse into the ocean after it is discharged. This modelling helps us design diffusers that would work best for the specific site conditions. 

Airborne Electromagnetic (AEM) surveys are used worldwide to explore underground resources using electromagnetic technology. The surveys help to map out hydrogeological features we can’t see above the earth’s surface – like the location and make-up of groundwater resources.  

The information gathered from this survey will assist us in further understanding the groundwater systems beneath the South Coast Peninsula. 

This will help us make informed decisions on future source planning, ensuring we continue to sustainably use the groundwater resources within a changing climate. 

The AEM survey is designed to characterise the conductivity properties of the ground by using an electromagnetic (EM) field. An EM field is transmitted from the loop towards the ground, and if a conductive body (like saline water, mineralised rocks or clay rich formations) is present in the ground, a secondary field is produced and picked up by a receiver in the centre of the loop. 

The data received is processed and converted into an electrical conductivity and depth profile.The results help us determine the presence of confining layers and map things like saline water interface or aquifer depth to understand the extent of the fresh groundwater resource that is suitable for water supply. 

The health and safety of the communities we service is extremely important to us. 

No harm is caused to plants, animals or humans from the electromagnetic loop. The EM fields emitted by the loop are similar to those produced by power lines which we pass by daily. As the helicopter or aeroplane flies quickly in the air, exposure to anyone on the ground is extremely limited. 

The flight paths are specifically designed for each area being surveyed. They are designed to collect data over open spaces and to avoid urban areas and structures with people or confined livestock. The flight lines will generally include a buffer zone to allow space for turning and deviating around built-up areas. We make an effort to work with the community to address any concerns they may have.