Reuters

San Francisco's sources of drinking water are threatened on multiple fronts.

People love living in the San Francisco Bay Area. They love it so much that the region’s population is projected to grow from 7 million today to 9 million by 2040. All those folks are flocking to the region to be part of an enormous economic success story.

Trouble is, all those people are going to need water. Water to drink and flush their toilets and wash the windows on those shiny new office buildings. Right now, there is enough to meet the demand, according to “Future-Proof Water,” a new report from the Bay Area good-government organization SPUR. But thanks to climate change, rising sea levels, and the likelihood of major earthquakes, that could all change very quickly. The water supply that sustains all this activity could be dramatically reduced, compromised, or disrupted.

According to Laura Tam, SPUR’s sustainable policy director and one of the authors of the report, planning has to begin now to avoid water shortages in the future. She explains that the area’s always fragile sources of water, which have long been the subject of political and environmental battles, are threatened on multiple fronts.

As sea levels rise, coastal aquifers, a major source of the region’s fresh water, could become infiltrated by salt water. At the same time, the snowpack in the Sierras – another primary source of water, flowing through pipelines hundreds of miles long to slake the Bay Area’s thirst – is projected to melt earlier and faster as the effects of climate change accelerate, a pattern the current system is not prepared to deal with. Under one scenario, as precipitation increasingly falls in the form of rain, only 20 percent of the snowpack will remain by the end of this century.

Climate change projections also indicate that the intermittent droughts that are a fact of life in California will intensify. “Climate change is going to affect the frequency, length, and duration of droughts,” Tam says. And that could spell trouble for some parts of the Bay Area. “Most places are OK in a normal year,” says Tam. “But in a very dry year, there’s a gap between what we have and what we need.” If a drought stretches into multiple years, says Tam, the gap could become huge – 21 percent regionally by 2035, and as high as 51 percent in one of the area’s 11 major water districts.

And then, this being California, there will be earthquakes. According to the U.S. Geological survey, there is a 62 percent chance of an earthquake measuring 6.7 or higher hitting the Bay Area in the next 30 years. A temblor of this magnitude could potentially rupture as many as 10,000 water pipelines in the region. Earthquakes also threaten the levees in the Sacramento–San Joaquin Delta, which provides water to 25 million people in the state of California. A major seismic event could interrupt that flow for up to a year and a half.

This is a threat that extends way beyond the San Francisco Bay Area. “I’m not sure if people in Southern California are aware of how vulnerable they are,” says Tam.

Raising awareness of the system’s weaknesses is one goal of SPUR’s report. “Future-Proof Water” also presents a series of concrete and relatively simple recommendations for increasing the resilience of the supply lines. Better storage of water in “wet years” and much more recycling and reuse of water are other recommendations. Desalination is given lowest priority, because of its high cost in energy and dollars.

SPUR’s researchers write that securing the supply won’t be enough, however. As the region’s population grows, efficiency of use and reuse will have to grow if the Bay Area isn’t going to find itself running short.

The report suggests targeting demand with pricing reforms and requiring retrofits of existing buildings to increase water efficiency when they are resold. New development, the report says, should be “highly water-efficient through green building ordinances” or require “water neutrality” by requiring developers to pay for retrofits and improvements that would reduce the net impact of their buildings to zero.

One important factor, says Tam, lies outside the jurisdiction of water companies: land-use regulations. “Places like San Francisco have been able to become so efficient in their water use because of density,” she says. But a lot of the region’s new development has been in more traditional suburban patterns, water-guzzling lawns and all. That kind of growth, says the report, should be discouraged. Because with a water supply that is under pressure from climate change, rising sea levels, droughts, earthquakes, and an ever-growing population, watering the grass shouldn't be a priority.

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