Awaiting Day Zero: Cape Town Faces an Uncertain Water Future

Cape Town’s predicament provides a global warning about the difficulty of ensuring water resilience in a warming world, even if, as with Cape Town, climate change is firmly on the agenda of city managers. Most climate models predict that the Cape Town region will become not only warmer, but drier, which bodes ill for a metropolitan area whose population has roughly doubled to 4 million in the past three decades and continues to grow at 1 to 2 percent annually.

And Cape Town’s rushed efforts to boost water supply by tapping into aquifers, including some in national parks and provincial nature reserves, are damaging valuable ecosystems and putting rare species at risk of extinction. The agricultural sector, including the Cape region’s world-renowned wine industry, has been forced to sharply cut back on irrigation, which is reducing production and leaving tens of thousands of people out of work.

So how did Cape Town, one of the best-managed and wealthiest cities in Africa, find itself on the brink of running dry? The city has, after all, won awards for its work on climate change. South Africa has some of the world’s most detailed, progressive water laws and deep expertise in water science and management, climate science, and meteorology. The city has mapped projected sea level rise and convened countless climate change adaptation planning sessions. Last year, Cape Town’s mayor said, “We cannot plan anything without factoring in the impact of climate change.”

A simple (and perhaps simplistic) answer to the cause of the current crisis is that rainfall was well below average for three years in a row, that no one could have or did predict that, and thus serious action to reduce water consumption — which should have begun in 2016 — came too late.  The crisis has exposed significant weaknesses in scientists’ ability to forecast weather on a seasonal scale, which is when it matters to city managers and farmers, and predict rainfall on an annual or decadal scale, which is when it matters to developers of large-scale infrastructure, such as raising dam heights and building desalination plants.

The southwestern part of South Africa has a Mediterranean climate much like the central coast of California, with hot, dry summers and cool, rainy winters (June through August.) The winter rains fill the six large dams around the city that form the core of the Western Cape Water Supply System (WCWSS), which services the vast majority of the city’s residential and industrial water users, as well as farming areas and smaller towns nearby.

The winter rains are generally very reliable. Using historical rainfall data, Piotr Wolski of the Climate Systems Analysis Group at the University of Cape Town has determined that a multi-year drought as severe as the current one would only be expected once every few hundred years, perhaps less than once in a millennium. The ongoing drought in the catchments of the WCWSS dams, he writes, “is indeed very, very rare, and thus very, very severe.” The historical rainfall record indicates that, having had two poor rainfall years in a row (2015 and 2016), the chances of a third bad year – especially one as bad as 2017 – were extremely remote. 

In addition to historical data pointing to the extremely low likelihood of 2017’s winter being dry, the South African Weather Service modeled a three-month seasonal forecast for the winter of 2017 that predicted higher than average rainfall. Notwithstanding that seasonal rainfall forecasts for the Cape region are notoriously unreliable, it appears that officials were left feeling less urgency to impose hugely unpopular water restrictions or push forward with expensive water infrastructure projects early in the year.

Experts have long warned that Cape Town would find itself in a water crisis caused by converging drought, population growth, and the failure to secure new water resources. But because of uncertainties in water consumption rates and in weather and climate prediction, it’s been hard to fix a date. 

“Water security has always been seen as ‘important’ in Cape Town, but until recently it has not been seen as ‘urgent,’” says Christine Colvin, head of freshwater programs with WWF-South Africa. “We have an HIV/AIDS epidemic, an education crisis, massive unemployment — these are understandably ‘urgent’ to politicians” and have competed successfully for attention and funding. Add to this South Africa’s fractured government institutions, corruption, and the fact that the national government is responsible for bulk water infrastructure like dams, but municipalities are responsible for water distribution and demand management, and you have a recipe for inaction on major water projects. 

In addition, Colvin says, the City of Cape Town raises significant revenue from water sales to residents, so it has never seriously incentivized individuals to conserve.

But as the magnitude of the growing water shortage became clear last year, Cape Town officials responded with an aggressive conservation campaign. Last June, all use of municipal water outside the home was banned, meaning no car washing or garden irrigation. In September, residents were limited to 23 gallons per person per day for all uses (washing, drinking, and toilet-flushing included) and at the beginning of February this year, the daily personal quota was reduced to a mere 13 gallons. Water pressure has been reduced across the city, slowing the flow from residents’ taps. And the municipality has installed tens of thousands of water-restriction devices on high-use households and has sharply increased punitive water tariffs for heavy users.

As a result of these and other measures, the city’s water consumption has fallen from 317 million gallons per day in early 2015 to about 137 million gallons per day. Day Zero has been pushed back from April 12 to July 9.

Cape Town is now scrambling to augment its rain-fed dams with other sources, mindful that a further year of drought is not impossible. Government has identified various options, including desalinating seawater, reclaiming wastewater (i.e. purifying sewage, as is successfully done in some other cities), and tapping underground aquifers. But desalination plants are expensive to build and operate, wastewater treatment plants are time-consuming to construct, and so the city has prioritized the hasty drilling of dozens of boreholes. Many of the drilling sites are in protected areas that are government-owned, which simplifies access.

Drilling boreholes and constructing pipelines, especially in conservation areas, would usually require environmental impact assessments and detailed environmental management plans. Because of the drought emergency, however, the provincial government has significantly relaxed these requirements, to the increasing concern of biologists and conservationists.

Cape Town is situated in the heart of the Cape Floristic Region, a distinct area of extraordinary biological diversity that contains 9,500 species of plants, about 70 percent of which are endemic. The Cape Floristic Region’s dominant vegetation type, popularly known as fynbos, contains many noteworthy species that are descended from ancient lineages. “These plants are like the Mona Lisas, the Rembrandts of the botanical world,” says William Bond, a botanist at the University of Cape Town.

Many of these plants are also dependent on seeps — permanently wet areas where underground aquifers naturally spill out on to the surface. Some are so rare that they only occupy single, tiny sites. “Drilling a single borehole in the wrong place could cause the extinction of a species,” says Bond.

It may already be too late for the Wemmershoek Erica (Erica bakeri), a diminutive heath-like plant with tiny pale-pink, bell-shaped flowers. About two weeks ago, the rushed construction of a water borehole and a pipeline trench commissioned by the municipality of Stellenbosch severely damaged a wetland in a conservation area. The wetland is the last known habitat for the Wemmershoek Erica, and one of the last known habitats for other critically endangered plants. “Goodbye… How many thoughtless flushes were you worth?” tweeted Cape Town ecologist Jasper Slingsby.

Notwithstanding the environmental impacts, there is enormous political pressure to proceed with borehole drilling. Biologists with the provincial nature conservation agency, CapeNature, have been forbidden to speak to the media. Nonetheless, documentation of environmental harm is leaking out: a spill of drilling mud that fouled a long section of a pristine river; maps showing more than 200 planned borehole sites in ecologically sensitive areas; and consultants’ reports showing drilling foam and toxic pump-test water spilling into nature reserves.

“We shouldn’t go blundering into these natural areas, but now it’s like the drillers have a blank check to do that,” says Bond.

Slingsby worries that once the boreholes are drilled, it will be politically difficult to turn them off, even if they dry up fragile wetland ecosystems. “I don’t know of any place that has given up water sources like that,” he says.

Almost all the Cape Town drought media coverage has focused on the city itself. Few reporters have paid attention to the rural areas around it, enormous acreages of which are covered in economically valuable vineyards, olive groves, and fruit orchards that require irrigation from the same six large dams and associated pipelines that sustain Cape Town. Farmers in the region have had their water allowance cut 60 to 87 percent, meaning that almost all irrigation was halted on February 1, even as many trees still carried fruit.

The Western Cape provincial government has estimated that 50,000 agricultural jobs will be lost this year, mostly among seasonal fruit-pickers, leading to about 260,000 people requiring poverty-relief assistance. Most of South Africa’s wheat is grown near Cape Town, and many wheat farmers will not harvest a crop this season. Agri Western Cape, a farmers’ union, says that farmers around Cape Town have lost about $1.2 billion due to the drought. Twenty-two percent of the sheep in the region have been culled because of a lack of fodder.

Francois Viljoen of Vinpro, an organization representing vine-growers and winemakers, estimates an overall harvest reduction of 15 to 25 percent this year. Even if good rains fall in winter, “we will see a carryover effect next growing season, with reduced yields, because the vines have not been able to build up reserves during the drought.” Because of smaller harvests, seasonal fruit-pickers will again have reduced income, with significant effects on poor rural communities.

No one can say how long Cape Town’s water crisis will last. Even if good rains fall this winter, tight use restrictions will likely remain in place indefinitely; the dams have been drawn down so far that it may take years to refill them, and water augmentation projects may take years to scale up.

Longer-term, a changing climate may well add to Cape Town’s water pressures.

“The models agree that Cape Town will become hotter over the next century,” says Peter Johnston of the University of Cape Town’s Climate Systems Analysis Group. “Most of the models — but not all — predict that it will become drier, too.” Increasing the city’s water resilience will mean expanding supplies from sources like desalination plants that are not as influenced by the vagaries of rainfall as the current dams. But these are expensive and energy-intensive, and residents will pay more, perhaps significantly more, for water.

The government will have to roll out new infrastructure amid considerable uncertainty about rainfall in the coming years, running the risk of over- or under-spending. Willem Landman of the University of Pretoria says that meteorologists “can make a reliable weather forecast that works for five days” and climate scientists “can model the average climate conditions a hundred years from now with a great degree of confidence. But decadal predictions? Forget about it. We don’t know how to set the models up. We can’t say what the rainfall is going to be 10 years from now.”

The question of whether Cape Town has moved into a new, climate-changed, normal, with more frequent droughts, is not easy to answer. “We’re out of the envelope of certainty,” says Christine Colvin. “Cape Town is not special. Many other cities will face these challenges in coming years.”