Protecting our water resources and securing water supply are essential for Perth’s future.
Each year, as the population grows and winter rains fail, concerns grow about our water security and amenity.
The Gnangara Mound – a name given to several aquifers that underlie Perth and supply half of our scheme water – is badly depleted.
This ‘fossil water’ source, in parts up to 37,000 years old, is recharged by rainfall but due to reduced rainfall, land use change and over-abstraction, the Mound is declining and many lakes and wetlands have dried up.
Seawater desalination now provides about a third, or 100 billion litres, of Perth’s scheme water supply, with another 50 billion litres due to come on stream by summer 2012-2013.
The Water Corporation says desalination is a “climate-independent” water solution but in truth desalination is vastly expensive and energy-intensive, thus in itself contributing to climate problems.
Other new water supplies pursued by the Barnett Government include drawing water from deep aquifers in the Gnangara Mound, with the aim of leaving intact surrounding aquifers. But this at best can be only a partial solution because over-use of deeper ‘confined’ aquifers’ will eventually lead to depletion of aquifers near the surface.
Re-use and recycling
Meanwhile, positive steps are being taken to increase water re-use and recycling.
A plant to be completed in late 2012 at Beenyup will recharge treated wastewater into the Leederville Aquifer, thus potentially freeing up additional groundwater supply. If the trial is successful, in future up to 35 billion litres-a-year of treated waste water may be recharged to groundwater annually.
Alison Xamon's water objectives
As WA Greens Water Spokesperson, Alison Xamon wholeheartedly supports increased water re-use and recycling, including, where appropriate, aquifer reinjection, storm water recycling, industrial water re-use and grey and black water recycling.
Currently Perth has the highest water use but lowest water recycling of Australian major cities, recycling just 6% of effluent, whereas Brisbane recycles 37% and Adelaide 30%.
Alison is also calling for other measures to secure Perth’s water future, including:
• Licensing and metering all commercial bores and ensuring compliance. Alison’s investigations have revealed that of the nearly 2000 users licensed to extract more than 5 million litres a year from the Gnangara Mound, less than 40 per cent have a metering condition on their licence, and only 27 per cent are actually reporting their water use.
• Penalising repeat offenders who use more than their licensed bore water allocation. Alison’s investigations showed that in 2010-2011, 169 licensees on the Mound took more than double their water entitlement, amounting to nearly 9 billion litres of over-abstraction – and these figures are from just the metered bore users, not from the many who are not metered.
• Making long-term, binding, water conservation targets a condition to operate for all water utilities. This will mean that utilities such as the Water Corporation are legally responsible for meeting water conservation targets. The WA Greens have been calling for this since they introduced a Bill for such legislation in 2008.
• Reviewing, updating and expanding the WaterWise program, to assist householders and small businesses to improve their water efficiency without loss of lifestyle. The Liberal-National Government cut the WaterWise program on coming to office but while it may have been in need of review, there are many ways now being neglected whereby households and small businesses could be assisted to save water.
• Investigating ways to expand water pressure trials, where appropriate, to recoup the estimated 10% of water loss that occurs through leaking pipes and firefighting activities.
• Greater transparency, including third party rights of appeal, in the granting of ground and surface water licenses. WA is blessed compared to other parts of Australia with considerable groundwater resources. However many of these sources are over-allocated. Elsewhere, there is strong competition for their use by competing mining and agricultural interests or to meet household demand. Licenses should only be granted after independent scientific assessment of the extent of the water resource, predicted rates of recharge taking into account climate change, and the water needs of local ecosystems. In addition, licensing decisions should take into account assessment of the relative social, environmental and economic benefits and costs of competing water uses.