Perth turns to groundwater as the city gets fuller, and drier
By the late 1960s, hydrogeologists had begun to appreciate the extent of the groundwater reserves beneath the suburbs. And not a moment too soon: thanks to the end of the embargo on iron ore, Perth’s economy was booming, attracting a wave of newcomers to the city. The rapidly growing city, however, was entering an especially dry decade. The state’s water utility began to add groundwater to the city’s supplies, sourced from the Gnangara Mound in Perth’s north. Compared to other potential sources, such as piping water from the state’s northwest, groundwater was easily accessible, and therefore, affordable. By the end of the 1970s, nearly half of the city’s water supplies were drawn from groundwater reserves. Today, the Australian Bureau of Statistics estimates that about a quarter of Perth households have their own bore.
At this time, the government imposed voluntary water restrictions, but as conditions worsened a tougher regime was introduced. Much to the ire of local gardening enthusiasts, residents could only water their gardens by hand at specific times. Accompanying these restrictions was a government campaign to encourage households to sink their own backyard bores, which could supply unregulated water for gardening purposes. To reduce the demand on reticulated supplies, subsequent governments continued to promote these unmetered and unmonitored water supplies until 2010, when their use became subject to water restrictions. Today, the Australian Bureau of Statistics estimates that about a quarter of Perth households have their own bore.
Although water restrictions and groundwater combined to ease the pressure on Perth’s water supplies, the state government concluded it was no longer feasible to keep pace with unfettered demand. To further curb consumption, the government introduced a user-pays system in 1978 that contributed to a significant reduction in household water use. In many suburbs, this reduction was focused outside the home, as residents adjusted their watering habits and garden tastes. Thanks to the increasing commercial availability of Australian plants, the government and local nurseries promoted bush or native gardens as a means to reduce household water use. Education campaigns during the 1980s continued this effort to temper domestic profligacy, which went some way to limit public backlash to the introduction of modest water restrictions in the early 1990s.
A desperate government builds Perth’s first desalination plant
On the eve of the twenty-first century, the Millennium Drought had begun to bite in the nation’s east. In Perth, the dry winter of 2001 delivered the lowest stream flows to the city’s dams since the drought of 1914. These conditions confirmed fears among local water managers that the region’s climate was undergoing a drying trend. The average streamflow into Perth’s dams had almost halved since the 1970s, and has declined further since. In response, the government increased its draw on groundwater reserves and tightened water restrictions, but not to the severe extent as elsewhere in the country. This reluctance to curtail water consumption was a legacy of the unpopular restrictions of the late 1970s.
To mitigate such circumstances in the future, the government announced in 2002 its intentions to develop a seawater desalination plant to supply water for Perth. Opposition from environmentalists, rural politicians, and the press led the government to explore alternative options, such as tapping the South West Yarragadee aquifer in the South West Capes region and piping water from the Kimberley. Neither plan held water, however. After achieving a second term in 2005, the Labor government proceeded with its plan to add desalinated water to Perth’s network and the city’s first desalination plant opened in late 2006. Other state governments took note, and before long, desalination plants were planned in similarly drought-affected areas, including the Gold Coast, Sydney, Melbourne and Adelaide. Loathe to impose tighter restrictions, the state government commissioned a second desalination plant, which was completed in 2011 – just after another record dry winter.
Meanwhile, the groundwater reserves of the Swan Coastal Plain were deteriorating under the stress of a drying climate and the thirst of the suburbs. Some wetlands had experienced fires and greater acidity, while vegetation had collapsed at others. In an effort to remedy their decline, the government commenced a trial in 2011 to replenish the Gnangara Mound with treated wastewater. This program of aquifer recharge or groundwater replenishment was surprisingly uncontroversial – compared to ‘Poo-woomba’, for example. Following methods practiced in California’s Orange County and elsewhere, recycled wastewater is added to groundwater reserves, which compensates the amount extracted for water supplies. The government has since expanded the program of replenishing groundwater with treated wastewater, with the aim to make Perth’s water supplies “climate independent” by 2022.