The Canal From Hell

When the rainy season starts this month, dozens of places in Mexico City will overflow with gray flood-water. Drivers will stall on the highways, subway riders will tiptoe through the muck and stores will sell loads of platform shoes. City workers will pump away massive quantities of water, but there is no stopping the inevitable. Since the Aztecs built Mexico City on a lakebed in a bowl of mountains nearly 700 years ago, its rulers have been struggling with the same problem: how to prevent residents from drowning in rainwater and their own effluent--much of it now swelling out of a canal of sewage in their midst.

Stories of Mexico City's pollution usually begin and end with toxic smog. But the saga of the Grand Canal--the public-works project from hell--offers even more dramatic testimony of man's abuses and nature's revenge. A century ago it was designed as the grand solution: a 29-mile drainage ditch (all but five miles of it aboveground) that carries sewage and rainwater out of the city and under the mountains. It remains a central artery in the drainage system, but exploding population growth long ago overwhelmed its capacity.

Now engineers are battling gravity as well. The canal once flowed downhill, but as the city taps its aquifer for diminishing supplies of drinking water, the clay lakebed is collapsing. The downtown plaza has sunk 29 feet over the past 100 years, and the canal has sunk as well--forcing the city to pump sewage uphill through a series of locks to get it out of town. The combination of water shortage and sewage excess has city officials quietly discussing a controversial idea: recycling drainwater into drinking water. "The challenge is not trying to convince people of the benefits of this option," says Antonio Dovali, director of the city's drainage system. "It is to convince the people that we don't have options."

A trip down--or, rather, up--the Grand Canal reveals an environmental disaster. In 1940 the metropolitan population was 2 million. Last year it topped 18 million people, generating 13,000 gallons of sewage every second. The big ditch starts in a downtown working-class neighborhood, where it resembles a long and oily lake coated with garbage. During the rains, 28 pumps churn furiously to push the water forward. Five miles ahead, the Deep Drain branches off: an underground tunnel 30 miles long and 21 feet in diameter that also is beyond capacity.

By the time the Grand Canal reaches the six-mile mark--the line between the city proper and the state of Mexico--the water burps methane and sulfuric acid. After five minutes on the shore your eyes begin to burn, and you know how somebody like Emilio Cortez Mendez feels every day of his life. A decade ago Cortez arrived with his wife and two children from the fields of Veracruz, found an abandoned concrete sewage tunnel and turned it into a rent-free apartment. Since then he and his wife have had four more children, and five more families have erected shanties next to the canal. Cortez, 37, monitors two boxes that send water-level data to a pumping station; in return the city gives him electricity and one spigot of potable water. "I don't live badly," he says. "I have all this, made from cement and concrete."

Multiply Cortez by 200,000--the annual population increase in Mexico City--to understand the growing water shortage. The government is reopening old wells, encouraging conservation, recycling some wastewater for industrial use and repairing leaks: 30 percent of potable water is lost because of pipes that crack under the sinking city. Still, a million people don't have a steady supply of water. In Unidad Valle Ecatepec, the small town that hugs mile 11 of the canal, Abdias Cruz, who runs the water station, turns the water on and off throughout the day to let the cistern refill. The water stays off while he sleeps--though he is never far away. "I don't have money to pay rent," Cruz shouts to be heard over an air compressor, which sits next to two beds, a kitchen table and a gas stove. Cruz, who earns $30 a week, lives in the pump house with his wife and 7-year-old son.

What bothers his neighbors more than the staggered water schedule is the odor of the canal, which often seeps through the drains into their apartments. "Above all in December," says 45-year-old Angela Sanchez. "It always smells the worst then." Most Mexico City wastewater come from homes, not industry, but it's still dangerous. "Living near the canal is risky," says Gregorio Martinez, a chemical engineer who monitors water quality for the city. "You are breathing toxic gases. And there is a high concentration of pathogens--bacteria like E. coli and Giardia and parasites."

Mexico City residents may be drinking that water in a decade--after it has been treated. Dovali, the drainage boss, says purifying wastewater and pumping it back into the aquifer would improve drainage, slow the sinking of the city and provide sufficient drinking water. "From toilet to tap," Dovali calls it. Other officials are more sensitive. The head of the city water commission, Leopoldo Rodarte, says planners need to study the idea for at least three more years: "We don't have sufficient technology to make this decision."

Canal water is already in demand--by farmers competing for it near mile 17. There the banks are sown with alfalfa and maize, surrounded by irrigation ditches carrying canal water. The farmers pay the city $70 each time they irrigate two hectares, but in the dry season the government rations it among eight farming cooperatives. The crops are supposedly used only as livestock feed, but that is not always the case. "We eat the maize. What other choice do we have?" says 63-year-old Lorenzo Sandoval Lozado, who has farmed the banks of the canal since he was 16.

The irrigation water comes directly from the canal. A massive new pumping station pushes water to a hillside tank, where it is stored until the fields grow thirsty. By the time the canal reaches the station, the water carries so much garbage that two-man crews work 24 hours a day to pull the trash up on hydraulic lifts and use pitchforks to load it into wheelbarrows. The trash soon becomes somebody else's problem: the workers wheel it to the shore 50 feet downstream and dump it back into the canal. "What else can we do with it?" says Pedro Hernandez Martinez, 40. The only things he doesn't throw back are the body parts. He calls the police to handle those.

Sometimes the canal swallows people forever. Three divers recently combed a side channel for the body of a 1-year-old boy who had fallen in. The divers, who earn $500 a month to descend into the drainage system several times a week, describe the water as "thick," impenetrable by light. Below the surface they work blindly, talking into a microphone to a radio operator above, feeling around for clogs and leaks, stepping lightly for fear of glass and nails. "Down there you feel the adrenaline," says Luis Covarrubias Bocanegra--he was born with that name, the last part of which means "black mouth." For the past 17 years, after each dive he has scrubbed his entire body with disinfectant. As for the baby, the divers gave up after a day of searching.

The canal itself soon disappears. In its final stretch aboveground it passes a carp-filled lake known as the Zumpango Lagoon. During the rainy season the flow is so heavy that the canal is channeled into the lake temporarily. Health authorities say eating the fish from it can cause hepatitis, a warning that hasn't stopped the locals from selling them fried for 30 cents a pound on the roadside. A dam lets out bacteria-ridden lakewater for its journey under the mountains. At mile 29 a waterfall shoots out of three giant metal gates into a white-capped wave pool that sprays a foul mist dozens of feet into the air and disappears into a seven-mile tunnel. The black water flows into the valleys, drains into several rivers and trickles through the countryside to the Gulf of Mexico.