Securing our groundwater future
All water users have a part to play in adapting groundwater use to the drying climate. We can all contribute by rethinking how we use, manage and interact with water in our homes and businesses.
To maintain groundwater as a viable resource for ongoing use and other public and environmental benefits, we need to stabilise groundwater levels and enable some key areas to recover. The Gnangara groundwater allocation plan: draft for public comment sets how much groundwater use will reduce over the next 10 years to rebalance the system and recover important ecological sites.
To help achieve a better balance, some local governments and businesses are already investing in water-efficient technology, investigating managed aquifer recharge and applying water sensitive urban design.
New urban developments can also be an opportunity to promote alternative, local water supply solutions that are fit for purpose, especially for the irrigation of public open space.
All water users will need to consider options like these and use water more efficiently to adjust to reduced groundwater availability.
Strategies to rebalance Gnangara in a drying climate by 2032
Groundwater will continue to be an important part of Perth’s water supplies because it is our lowest cost and most accessible water source.
Reduced abstraction is a key part of the solution as we adjust to less rainfall. How we will reduce abstraction and measure the success of this is outlined in the Gnangara groundwater allocation plan: draft for public comment.
Land-use change such as urban expansion and harvesting some of the pines from the Gnangara Mound will improve recharge to groundwater, which will reduce the effects of lower rainfall in some places.
Science and research play an important role in solving emerging water problems. The Department of Water and Environmental Regulation has used the latest scientific data in the draft plan and continues to research and advise on groundwater resources and management.
Exciting finds in science
One of the goals of the Department of Water and Environmental Regulation’s $7 million Perth regional confined aquifer capacity study – Studying Perth’s deep aquifers to improve groundwater management – was to see whether we could optimise the way we take and use water from the Gnangara system, including new locations to draw water from deep aquifers that have less impact on the system.
The study used robust and established science, coupled with innovative research, to improve our understanding of the deep Leederville and Yarragadee aquifers in the Perth region. Recommendations from the study that supported our allocation planning for the Gnangara system included:
- reduce the volume of deep aquifer groundwater abstraction over time in targeted locations – this will contribute significantly to rebalancing the Gnangara groundwater system
- focus the abstraction reductions in parts of the deep aquifers near where they are connected to the Superficial aquifer.
We used the findings of the study to guide the development of Water Corporation’s groundwater replenishment scheme which involves treated wastewater being further treated to drinking water standard and then recharged into aquifers for later use as public water supply. The study helped determine suitable locations for recharge and abstraction that support full recovery of the volume of water being recharged and provide improved water resource and environmental outcomes.
Water efficiency and innovation
Efficiency and innovation will be key to making Gnangara groundwater stretch further and be more sustainable as a resource.
Reducing demand through efficiency:
- increases productivity
- minimises water costs
- avoids or delays the need for new water sources.
Through the Waterwise Council Program, more local councils are becoming more water efficient, improving turf maintenance practices and adopting new irrigation and water monitoring technologies. We now have a Waterwise Irrigation Training Program for Gold status Waterwise Councils in partnership with Water Corporation and Irrigation Australia Limited Western Australia.
Some developers, schools and businesses are also succeeding through water-sensitive urban design. Good design is essential for reducing water use as well as for managing stormwater and enhancing recharge. The department is advising land developers in Perth’s new growth areas on opportunities to access tradeable water entitlements, water sensitive urban design and, where needed, options for additional water supplies.
Households are helping to save groundwater by being more waterwise in their homes and gardens. Waterwise gardens include native and drought-tolerant plants, mulching, and efficient, well-maintained irrigation systems. One of the great side benefits of these practices is the simple fact that they save money.
The Be Groundwater Wise website provides information to help garden bore owners understand their bores, the importance of groundwater and how to be waterwise with bores, irrigation systems and gardens. State Government is further assisting householders to make their gardens more waterwise through education campaigns and incentives to invest in smart irrigation technology and spring sprinkler system check-ups.
Some agricultural businesses have become very efficient through use of contemporary technologies, irrigation schedules, improved maintenance and better management. The combination of crop types, crop areas and the type of irrigation systems used can also boost water efficiency. State Government is investing $750,000 in targeted programs to support the horticulture industry in North Wanneroo.
Leaders in water efficiency and innovation are showing that we can all adjust to a drying climate by rethinking how we use water.
Boosting water supplies
The Water Corporation already has two seawater desalination plants, which can provide up to 50 per cent of the metropolitan area’s scheme water needs. Desalination has given us a secure water source for part of Perth’s drinking water supply that doesn’t depend on the rain.
Groundwater replenishment where large volumes of highly treated recycled water are recharged back into deep aquifers to augment our drinking water. Construction of Perth’s first full-scale Groundwater Replenishment Scheme at the Beenyup facility in Craigie is now completed with a capacity to recharge 14 GL of recycled water into groundwater for storage and abstraction each year. Work is underway to double the scheme’s capacity to 28 GL each year.
Managed aquifer recharge where water is infiltrated back into an aquifer through reinjection bores or ponds, basins and trenches for later use or to benefit the environment. Well considered location and design can deliver benefits for local water users and the environment.
Stormwater harvesting where rainfall runoff is captured in tanks or other storages as a water source that can improve water supply for non-drinking purposes in households or businesses and parks and gardens. Good urban design can enhance stormwater recharge to groundwater – a natural form of stormwater harvesting.
Wastewater treatment and reuse where wastewater is recycled to be used for irrigation of parks, public gardens and golf courses, and potentially other uses such as horticulture and industry.
The best alternative, non-potable supply may vary from place to place, and interested water users will need to carefully assess the range of options available and the costs and benefits of each.
Smarter solutions for recycled water
The City of Kalamunda is recycling winter drainage water, storing it through managed aquifer recharge, and using it to irrigate parks in summer.
In response to reduced groundwater availability and local salinity issues, the Western Suburbs Regional Organisation of Councils investigated new ways of using recycled water to irrigate parks and public open space either directly from the Subiaco treatment plant or by ‘topping up’ the Superficial aquifer for reuse later.
The Department of Water and Environmental Regulation is also partnering with the Department of Communities, the City of Swan and developers to consider water supply options for the Department of Communities’ Brabham development in Perth’s north-east.