Australia, like California, is accustomed to living through dry spells. Also like California, which is currently in the grips of its deepest drought on record, Australia recently experienced its longest and most severe drought on record: the “Millennium Drought,” which lasted from 1997 to 2010. Though the drought affected all of Australia, its most devastating effects were concentrated in the populous southeast part of the country, home to the four largest cities of Sydney, Melbourne, Brisbane and Adelaide. Its impacts were wide-ranging and felt by everyone. Cities had to implement severe water restrictions, including, in some places, a complete ban on outdoor water use for years. With irrigation curtailments and no rainfall, farming all but disappeared in the agriculturally rich Murray-Darling river basin, which normally produces one-third of Australia’s food supply. The environment suffered as well: stream flows were reduced 80 to 90 percent, over 70 percent of floodplain forest died and several species were newly threatened with extinction.
How did Australia respond to its historic drought, and what can California learn from Australia’s experience?
Leading up to and early on in its drought, Australian cities and utilities began planning to diversify water supplies and to scale up efficiency and conservation programs. California cities and water suppliers have been doing this for many years, spurred by state laws that set per-capita water use reduction targets and require water agencies to do long-term supply and demand forecasting. 
As in California, water conservation was embraced in Australia as the easiest way to extend the availability of limited water supplies. In the late 1990s, the Sydney Water Company (SWC) received a state mandate to reduce per-capita water consumption 35 percent by 2011 — to the equivalent of 86 gallons per person per day. This aggressive target, set before the Millennium Drought arrived, led the utility to experiment with and refine water conservation programs that were then scalable when the drought arrived in full force. SWC’s water efficiency home retrofit program, WaterFix, for example, became a model for the country. Half a million homes enrolled in the program, which included a water use audit, leak fixes and fixture replacement with high-efficiency models and flow control devices (3,000 signed on per week during the peak of the drought in 2006 2008). Other significant program investments that drove down water consumption included washing machine rebates, toilet replacement services and rainwater tank installations. The Sydney region succeeded in exceeding its water use reduction target five years early, and has sustained that level of water efficiency even after the drought ended in 2010. Today, the region uses less water in total than it did 30 years ago, even while it has added a million people. 
As the drought worsened, SWC and utilities around Australia began pursuing supply-side measures, in anticipation that surface supplies could entirely dry up and conservation would no longer be useful. The regionwide Metropolitan Water Plan (2004, updated in 2006 and 2010) identified ways Sydney could diversify and build supplies beyond conservation programs, including a fivefold increase in recycled water, tapping groundwater and preparing to build desalination facilities. Though diverse water sources provide resilience and stability in the event of a shortfall in any one supply source, many Australian cities historically relied solely on rainfall and surface storage in the form of large dams. Eighty percent of the Sydney metropolitan region (4.5 million people), for example, relied on the capacity and storage of one large dam. Between 2008 and 2011, the drought spurred the construction of three major recycled water facilities in Sydney and many smaller ones built by private entities, some supported by public incentives. SWC launched a study of groundwater resources and “deep water” accessed under dams. Finally, as a desperate measure, the utility built a seawater desalination facility capable of supplying 15 percent of the Sydney metropolitan region’s daily needs.
Desalination of seawater, while providing a highly reliable water supply, is controversial because plants are expensive to build and energy-intensive to operate, and they produce a polluted brine that must be safely disposed of. And Australia’s desalination story should serve as a cautionary tale for California. Early in Sydney’s regional water planning efforts, desalination was studied as a “readiness” strategy that would be pursued further only if the region’s dam levels fell below 30 percent. As water levels fell perilously close to this mark in 2007 — the peak of the drought — a plant was designed and planned, and construction was allowed to proceed even as dam levels subsequently rose from 35 to 60 percent within one year. The $1.7 billion facility was finally completed and tested in 2010 but was shut down, unused, in 2012 as the drought had ended and the region’s dams were full. The well-intentioned effort has significantly raised the price of water to SWC customers as the plant costs over $300,000 a day in availability payments to its investors — charges that will continue for 50 years whether it ever produces water or not.
One can look at this investment as as a source of resilience in the face of climate change: Australia faces more frequent and severe heat waves and droughts if global greenhouse gas emissions do not rapidly fall.  Or, it can be seen as an over-commitment of resources that will keep water costs high far into the future, chilling the environment for innovation in conservation, recycling and more sustainable sources. When the region faces drought in the future, it seems likely that Sydney’s desalination facility will be utilized instead of the city inventing WaterFix 2.0 in collaboration with SWC, or investing in reuse projects or other less intense technologies.
Australia’s drought came to a biblical end in 2010 with record-breaking rainfall and flooding. The Murray-Darling Basin experienced its largest annual rainfall on record; the city of Sydney experienced an overly wet year in 2010 and its wettest year in more than 150 years in 2011. The Millennium Drought’s end was a relief, but an ominous one. Climate change is expected to bring longer, drier droughts, and unpredictable, potentially more intense rainfall to Australia and California alike. Both places are expecting urban population growth, which will require more water. Both need to consider a changing climate in planning for a reliable water supply, and both know that water efficiency and conservation is the least-cost, most sustainable path toward it. California can do more to scale up the water efficiency programs that Australia succeeded with in achieving unprecedented low per capita water use. But California can also learn from Sydney’s response to the Millennium Drought — 13 years long to our current 4 — that scenario planning and adaptive management can help avoid getting locked into investments that limit the ability to take a soft, resilient path in the future.
1 The Water Conservation Act of 2009 (SB X7-7) and The Urban Water Management Planning Act of 1983, respectively.
2 Alliance for Water Efficiency, University of Technology Sydney and Pacific Institute, “Managing Drought: Learning from Australia,” 2016.
3 The Climate Council, “Thirsty Country: Climate Change and Drought in Australia,” 2015.