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Public Radio's Environmental News Magazine (follow us on Google News)

A Thirsty City

Air Date: Week of

Water was the key resource that first attracted Mexico City's ancient residents, but may be a problem for the almost thirty million residents today. The interconnected lakes and deep aquifers that lie beneath the capital are drying up, and Mexico City is sinking. The water supply, treatment, distribution and waste disposal are all in jeopardy. And unless swift action is taken, the taps in the world's most populous city may soon run dry. Bob Carty reports.


CURWOOD: Mexico's capitol is celebrated in song as a city built on water. As legend has it, 7 centuries ago the Aztecs came on a series of lakes at the end of the central plateau. On an island they saw an eagle perched atop a cactus with a snake in its claws, and that's where the Aztecs founded their empire. Today, Mexico City has more than 20 million people, and when it makes the news it's often because of problems with air pollution. But it's water that's the source of so much conflict, disease, and increasing social friction. It's water that could eventually bring down this mega-city. As Bob Carty reports, every stage of the water system, supply, treatment, distribution, and waste disposal, is in crisis. And Mexicans are searching for ideas to avoid a futuristic nightmare.

CARTY: In downtown Mexico City, the 4 giant pillars of the Monument of the Revolution rise 100 feet above the street, supporting a massive dome that celebrates the history of the nation. In front, there's a fountain bubbling peacefully, in a way suggesting that all is well with water in Mexico City. But that is a lie.

(A fountain)

CARTY: Just walk over to the corner of the monument where a thick iron pipe sticks out of the ground. When this monument was built in 1934, the pipe brought in the water supply. It came up to ground level. Today the pipe sticks 27 feet up into the sky. But it's not the pipe that has moved. It was anchored deep into the bedrock. Instead, as groundwater was taken out of the clay soils beneath Mexico City, the earth has subsided. The city, like the Monument of the Revolution, has sunk 27 feet over 6 decades. The neighborhood kids have even made a game of it. On the iron pipe there are colored stripes where children mark their height, to see if they can grow as fast as the monument sinks and the pipe rises. The pipe is winning. It's a problem the first inhabitants, the Aztecs, could not have imagined.

ARIDJIS: When the Aztecs came to the Valley of Mexico, it was a valley of water, full of water. Full of rivers, full of canals, pine trees, was completely forested. It was one of the most beautiful views in the world at the time.

CARTY: Homero Aridjis is a poet and a novelist and the president of the Group of 100, an environmental organization of local artists. Aridjis explains that when the Spanish took over this valley they did not share the Aztecs' fondness for water. They wanted Mexico City to resemble the cities of their arid homeland. So they constructed canals and drained the lakes away.

ARIDJIS: The problem, it is very bad. Even I wrote a book, a novel, where the big problem is the lack of water. Mexico City without water any more.

(Music up and under)

MAN: (Recites) The city of lakes and rivers and liquid streets now had no water and was dying of thirst. The volcanoes had been lost from sight, and deforested avenues smouldered in a brown horizon. The year 2027 was coming to an end and the city was sinking.

ARIDJIS: I thought the crisis was coming in the year 2027, but now the crisis can be as soon as the year 2003, that Mexico City could be without water, if nothing drastic is done.

CARTY: And the drastic things that need to be done can be found at every stage of the city's water system, starting here.

(Fans and humming)

GUERRA: This was built at the beginning of the century and expanded since then. It's a water chloration and purification plant, and the quality of water that is still being pumped is still good.

CARTY: Manuel Guerra is a chemist and the director of the Independent Institute for Environmental Research. Standing outside of one of Mexico City's water treatment plants, he explains that the mega-city gets 72% of its water from wells, pumping water up 200 meters from the underground aquifer.

GUERRA: Mexico City, because it was covered with 5 big lakes, built during millions of years a huge aquifer that is now being depleted at the rate of 1 meter a year. We are extracting 3 times more water than what is going in, sinking in again because of the rainwater.

CARTY: The problem isn't lack of rainwater. Mexico City gets 2 or 3 feet a year. But it's concentrated in a short rainy season. With much of the city now covered in asphalt and denuded of trees, the rainwater has little chance to sink into the ground to replenish the aquifer. When it rains, the city uses huge underground tunnels to pump stormwater out of the valley. It prevents flooding, but each year the aquifer gets lower. Manuel Guerra notes that so far, the aquifer water is clean and drinkable when it leaves the treatment plant. But then things go very wrong.

GUERRA: The main problem is that due to the subsidence of the ground, to the sinking of the city, the pipes break. Pipes with sewage water and pipes with drinking water, so there's, say, mixing of both. And then you can have enormous health problems with that: diarrhea, big problems with cholera. Mexico City is a city on the planet with the highest consumption of bottled water, of course.

(Running water)

WILK: (Laughs) You're never sure about what's being delivered with the water in the pipe. At home we use at least 60 liters a week of bottled water for cooking and drinking.

CARTY: David Wilk is an environmental planner, and one of the authors of a major study on the water crisis, sponsored by the National Research Council of the United States and various Mexican research institutes. The study concluded that Mexico's exploitation of its aquifer is "nearing a crisis." But David Wilk says there are better strategies than the current practice of tapping into rivers 80 miles away, literally drinking them dry and pumping their waters 4000 feet up to the city.

WILK: The costs are outrageous because remember that Mexico City's at a very high altitude, and we need to spend more and more for every cubic meter of water that is being pumped up to the city. We have a major problem of leaks in the water mains in the city. Leaks are caused by subsidence, and from 35% to 40% of the water is being lost due to undetected leaks.

CARTY: That means that Mexico City wastes as much water as some of the world's largest cities use. But water leaks and shortages are not felt equally across Mexico City.

(A dog barks)

CARTY: In Ixtapalapa, a huge working-class slum, water is the source of growing social protest. Two million people in Mexico City have no running water. And those who do, like these 2 housewives, are not happy when they turn on the tap.

WOMAN: [Speaks in Spanish]

CARTY: The women say the water sometimes comes out in the morning, but by noon there's none. And when it comes out it's dirty. You can't even do your washing with it.

(A sprinkler system runs)

CARTY: It's quite another story across town, behind the walls and guards of an upper-class suburb. Here, sprinklers drench the grass with drinking water. In fact, a mere 9% of Mexico City's population, the rich and industry, use 75% of the water. And it makes the poet Homero Aridjis angry.

ARIDJIS: They wash the cars with drinking water every day. And sometimes they wash the sidewalks also, because they think that the water has no value. That this is a culture problem.

(A child speaks in Spanish about water; a man sings to music)

CARTY: The government is trying to correct that cultural problem with television ads on the virtue of using less water. But experts say what's really needed is a politically unpopular measure: raising the price of water. A bottle of cola here is cheaper than 250 gallons of tap water. Most water usage is unmetered, and consumers pay only 10% of the annual billion dollars spent on water services. You waste what you don't pay for, argues Manuel Guerra.

GUERRA: I would privatize the water distribution system to make companies responsible for bringing good-quality water into their homes. Install modern metering systems to double or triple the amount of money collected. People have to accept that paying for water is as important as paying for clothing or for feeding or for education.

CARTY: Wouldn't that hurt the poor, who in Mexico are very poor?

GUERRA: On the contrary. The people who pay the highest price for water in Mexico City are the poorest ones, because they have to buy water from water tanks, from water cars, that charge 10 times as much as City Hall for water. So, the poor are the most hurt with the present system.

CARTY: It is the final stage of Mexico City's water system that is the most threatening and repulsive. Homero Aridjis wrote about it in his novel The Legend of the Suns.

(Music up and under)

MAN: (Recites) A nauseating odor floated over the city. Cats, dogs, pigs, and rats appeared dead in the streets. The only things that ran with stinking punctuality were the rivers of sewage, the black waters and liquid garbage. Vile reminders of what was once the Venice of the Americas.

(Music up and under; fade to rushing water)

CARTY: On the east side of the city, 6 huge pipes belch out black sewage into an open canal. The liquid waste bubbles as it putrefies. The air is filled with floating bacteria. The stench is unbearable. Only 10% of Mexico City's sewage is treated. Most of it is pumped out of the valley, some going to irrigate crops even though it is laced with heavy metals and toxins. The rest winding up in the Atlantic Ocean. There are projects underway to cover the open sewage canals for health reasons. But the sewage treatment dilemma will not be solved for decades. And scientists are worried about what could happen in the meantime. The sewage does not yet contaminate the aquifer, the source of 72% of the city's drinking water, because it's protected by a layer of hard clays. But environmentalist Manuel Guerra worries that the sewage canals are a catastrophe waiting to happen.

GUERRA: The worst-case scenario for Mexico City would be a prolonged drought, let's say 3 or 4 years in a row, together with an important earthquake that could fracture the roof of the aquifer. That would allow waters like this, highly contaminated, to cascade into the aquifer 200 meters deep. That would put in jeopardy 20 million people. That would mean the end of Mexico City.

CARTY: That's why experts believe that the waste disposal challenge is as important for the city as its water supply. On the supply side, Manuel Guerra believes he has a possible solution. A solution which would simultaneously reduce the sinking of the city and therefore also reduce the waste of water through leaks and the risk of contaminating the aquifer. To explain his idea, Manuel Guerra takes me out to the middle of a multi-lane highway, where an old cement building houses a pump and a set of pipes disappearing into the ground.

GUERRA: Here we are standing in front of a well that previously extracted water from the aquifer. But some of the wells are unused now because they don't reach the water any more. They could very easily be used to gather water from extensive areas like streets, parking lots, roof tops of huge buildings like supermarkets and so on, that can gather water. It can be then filtered and re-infiltrated into the aquifer.

CARTY: Sort of reverse wells.

GUERRA: It's like a reverse well. Rain filtration wells instead of pumping out the water, allowing water back into the aquifer.

(Outdoor musicians)

CARTY: In the central plaza, the crowded meeting place of Mexico City, native drummers and dancers perform for the tourists. As with so many problems here, the water crisis is fundamentally one of too many people living in the same place. In the long run, what's needed are measures to reduce migration from the countryside, and to decentralize industry and government away from Mexico City. But in the labyrinth that is Mexican politics, such measures get scant attention. The notion of raising water prices is a non-starter, at least until after the next presidential elections. The idea of replenishing the aquifer with reverse wells is being ignored in government offices, despite the enthusiasm of environmentalists. And the city continues to sink, in some places by as much as 16 inches a year. Writer Homero Aridjis views it all with a sad sense of irony. He points out that the old Aztec pyramids, once buried beneath the central plaza and now uncovered, are slowly rising, in comparison to the nearby cathedral and government buildings.

ARIDJIS: The national palace is sinking. Every day we have to inject thousands of liters of water to keep the national palace floating. But it looks like a sinking ship. Now the place where the Aztecs choose as full of water is going to die for the lack of water.

CARTY: In Mexico City, I'm Bob Carty for Living on Earth.



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