On July 26, Mexico City authorities announced an emergency, 10-month water rationing plan in response to severe shortages resulting from an extended drought that has gripped the region since 1994. The National Water Commission, Conagua, warned in recent days that the seven reservoirs that make up the Cutzamala System, which supplies 24% of the Mexican capital were at dangerously low levels. (Over 70% is supplied by ground water, and the reservoirs are the sole source of water for 10 municipalities on the city’s outskirts.) Conagua, in response, plans to reduce the water flowing from Cutzamala’s dams in the southwestern state of Michoacan to 13 municipalities of Greater Mexico City by between up to 10% during the weekdays to 50% on the weekends; the goals is to reduce water use by 6.7 million m³/month, representing 3.5% of consumption. The 20 million residents of the giant metropolis were already hit with partial stoppages earlier this year, including a cutoff in April that affected roughly a quarter of Mexico City’s population.

Although the city’s mayor blames the crisis on global warming, demographics and ill-conceived management have played a far greater role in the local crisis – one that is now far too severe for temporary austerity measures to solve. The inhabitants of Mexico use on average 300 liters per day, roughly double that used in some water-conserving cities of Europe. Because the population is growing by 4% annually, water demand is expected to jump by 20% in the next four years to five years. The problem is further compounded by a self-reinforcing water withdrawal/leak cycle. Overdrawing groundwater has led to the land’s surface dropping by 10 centimeters per year. This causes the water distribution system to crack, which in turn has led to the loss of more than 40% of the water from water mains, yielding an equivalent demand for more groundwater.

The self-reinforcing nature of the problem makes it one that is particularly challenging and expensive to solve. Although the citizens of the city use a lot of water, nearly half of the “consumption” is in the form of leaks, so water restrictions on end use will be doubly painful. Those same leaks will also blunt the efficacy of water recycling. And because water withdrawal causes stresses that result in leaks, a slow piecemeal effort to replace pipes will not work. It seems that the only solution is to replace the entire distribution system within a few years; however, the Mexico City government has only allocated 770 million pesos ($57.8 million) to substitute water networks and capture systems and fix leaky pipes – a number orders of magnitude smaller than what’s required to rectify the problem. Given the political finger-pointing and token responses seen to date, it unfortunately seems unlikely that the needed investment will materialize. The city may very well have reached a tipping point where its only future is one of depopulation and decline.

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