Beijing itself is quietly sinking. With much of its surface water fouled by pollution—and a population that has exploded from 2 million in 1948 to 18 million today—the city relies on groundwater for most of its needs. But drought and overpumping are rapidly depleting the area’s underground aquifer, causing sinkholes that have destroyed factories and homes. Subsidence is threatening sections of the Beijing-Shanghai railway line and parts of the city’s international airport. “Subsidence security” is a major issue.

So it’s easy to see why many Chinese environmentalists regard the splashy Olympic site in Beijing as a Potemkin village. The rowing and canoeing venue is on the ­Chaobei River, but the Chaobei hasn’t flowed in nine years. To refill two miles of dry riverbed, organizers spent $57 million diverting 450 million gallons of water from the Wenyu River eight miles away. The Chaobei now boasts one of Asia’s most potent fountains, its water jet thrusting 450 feet in the air.

Almost half of the Olympic events will take place at the Olympic Green, a symbol of China’s pledge to throw a green Olympics. The 1,000 acres of wetlands, lawns, plazas, and stadiums are carved right into the concrete core of north-central Beijing. In 2004, as part of an effort to find an architecture firm for the Olympic Green and the adjoining Olympic Forest Park, China’s Olympic organizers asked for bold ideas in urban ecology. Sasaki Associates of Boston won the contest with a blueprint for an aquatic landscape of rain-fed canals and lagoons designed to support wildlife in the urban park. Within months, though, the plan encountered problems. “We saw it all unravel before our eyes,” says Mark Dawson, the project’s leader.

Chinese officials were concerned that locals would hunt any animals or waterfowl reintroduced to the city, Dawson says. The officials opted instead for a shallower aquatic system—decorative, not ecological—fed by an existing canal just north of the site. The American designers knew that farmers and others depended on that canal for water and felt such a diversion would be counter to the spirit of the green Olympics that China had promised. In the end, the project was reassigned to several Chinese design institutes.

Beijing’s water bank, in the surrounding Hebei Province, is broke. Among China’s provinces, Hebei ranks near the bottom for available water resources in per capita terms, at just 12 percent of the national average. In southwest Hebei, an obelisk atop Xidayang Dam, a two-hour drive from Beijing on jammed country roads, bears slogans from Chairman Mao glorifying the “taming” of China’s rivers. Built in 1958 by 84,000 workers, the dam created a reservoir that flooded 1,700 square miles, as well as the homes of 29,000 people. The reservoir supplies water to Baoding, a city of 11 million; next month, somehow, it will also supply the Olympics. Yet since 1996, its water level has steadily retreated; it’s now at less than 30 percent of its capacity. The drought has left the dam and a pair of pipeline-control stations looming 10 stories above the reservoir.

Downstream, in Wangdu County, villagers have turned a dried-up, tree-lined canal into a garbage dump. A pipeline from Xidayang now bypasses the villages, carrying water destined for Beijing via a new cement-lined channel that workers are rushing to complete for the Games. In Yan’s village of Shijiayao, summer rains cascade down the denuded mountainside, flooding paddy terraces and the access road. But with no storage facilities, the village can’t save the runoff. Yan says his people have but one hope: that the sprawling capital will grow to engulf them and thus permit them to tap their own water supplies.