If we want water security, we need to diversify our water sources to include underground storage, stormwater capture, recycled wastewater and more.
The word “drought” is once again entering the California vocabulary. As quickly as we exited our state’s historic five-year drought, signs are beginning to show that we are slipping back into another round. Of course, a “March Miracle” could still materialize, easing our insecurities, but we cannot let that be our only comfort. We — and others in similar circumstances around the world — need a strategy for reliably meeting the water needs of growing populations and economies in the face of increasingly dramatic swings in precipitation caused by climate change. The way to do so is by diversifying water sources.
As regions around the world have experienced periods of extended drought, we’ve seen how singular water supply sources can create crises when exhausted. Cape Town, South Africa’s second largest city and a mainstay of the nation’s tourism industry, is experiencing its worst drought in more than a century with its 4 million residents limited to using just 13 gallons of water per person per day as they count down to Day Zero, when municipal taps will be switched off. The city’s near-total reliance on rainfall-fed dams has led to its vulnerability.
Contrast the dire conditions in Cape Town and São Paulo with California, which is working to adapt to changing conditions.Similarly, São Paulo emerged from a two-year drought thanks to El Niño rains, but up until recently faced unprecedented water shortages that forced shutdowns and quotas. The nearly 20 million people who live in South America’s largest city depend on rivers and above-ground reservoirs to supply their drinking water and hydroelectricity for their energy. With industry accounting for about 30 percent of water use and experts predicting that droughts will be more likely in the future, private sector representatives have joined activists in urging government planners to diversify the city’s water supplies.
Contrast the dire conditions in Cape Town and São Paulo with California, which is working to adapt to changing conditions and rapidly becoming a model for the kind of balanced water storage and conveyance systems that other cities, states and nations need.
With about two-thirds of its precipitation falling in the north and roughly two-thirds of its population residing in the south, California relies on an intricately plumbed network of reservoirs, aqueducts, pipelines and pumps as well as out-of-state imports to supply water to major urban centers, agriculture and industry. A major earthquake or failure of a dam or levee could have a profound impact on the water supply to regions hundreds of miles away. In addition, the two major sources that feed the aqueduct systems, the Colorado River and Northern Sierras, are themselves strained by climate change, causing swings in their annual reliability.
None of these prescriptions alone is a silver bullet. But combined they offer reliable and flexible sources of supply to meet long-term needs.Faced with these vulnerabilities, California has set out on an urgent path toward ensuring water security not only for today’s users and conditions, but for future users and conditions as well. Agencies across the state are implementing new techniques and technologies in an effort to diversify supply portfolios to include not just traditional reservoir surface storage, but also underground aquifer storage, stormwater capture, recycled wastewater, and brackish and ocean water desalination where viable. None of these prescriptions alone is a silver bullet. But combined they offer reliable and flexible sources of supply to meet long-term needs. The focus is on resilience and sustainability, and we are looking to other countries, such as Israel and Australia, that have faced similar challenges for lessons learned.
One area in particular in which California and local agencies such as the West Basin Municipal Water District, where I have served on the board of directors since 2014, have made great strides is water reuse — recycling treated wastewater for irrigation, industrial use and groundwater recharge. The drought of the late 1980s and early 1990s led to the development of West Basin’s world-renowned Edward C. Little Water Recycling Facility in Los Angeles County. The facility recycles some 40 million gallons of water per day and distributes it through a network of 100 miles of distinctive purple pipes.
The use of recycled water during the 2012–2017 drought helped insulate West Basin from mandated conservation cuts.Where West Basin is unique is that it produces five types of “designer” recycled water that are specific to the needs of our customers. These include golf courses, local municipalities, and office and shopping centers that require irrigation water; oil and gas refineries, which use water to run boilers and convey heat to cooling towers; and residents, whose drinking water we help to protect by recharging our aquifers to prevent saltwater intrusion along the coast.
The use of recycled water during the 2012–2017 drought helped insulate West Basin from mandated conservation cuts by the state and allowed our customers to continue normal operations in the midst of severe drought. Today, we continue testing new recycled water technology that will benefit the entire water industry and are in the process of expanding the plant’s capacity to produce additional recycled water, further improving drought resilience and lowering dependence on imported potable water.
The increasing demand and fluctuating supplies confronting California, Cape Town, São Paulo and many other communities around the world emphasize the need for a new way of looking at water. As we encounter the effects of climate change and growing, wealthier populations, we must develop a more diversified approach to supply that takes into account regional natural assets, such as groundwater basins and seawater desalination, as well as supplemental systems including reservoirs, stormwater capture and recycled water. The costs of inadequate water supplies are steep for today’s highly condensed urban areas and are simply not an option.
(This artcile has been taken from Ensia).
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