Here, water irrigates endless fields of cotton, one of the main sources of income in this primarily agricultural land. Nurek  the world’s highest dam, at 984 feet, and a prestige project of the Soviet Union  is the difference between light and darkness, heat and no heat, for the majority of Tajikistan’s seven million inhabitants, supplying nearly all the country’s energy needs. It also provides cheap electricity to power the Talco aluminum plant, the nation’s largest industrial enterprise.

Rogun, as it is now envisioned, would surpass Nurek’s height by more than 100 feet.

Though for the moment it seems to be managing, Tajikistan threatens to become a failed state, say Western experts and diplomats, speaking on condition of anonymity because of the delicacy of the issue. The country still has not fully recovered from a devastating civil war a decade ago. State coffers are virtually empty, while the government is viewed as unable to meet basic needs.

The situation was laid bare last winter when prolonged subzero temperatures overloaded the Soviet-era electrical grid, plunging the entire country into cold and darkness. For Western officials working in Tajikistan, the emergency was a disturbing revelation of the government’s dysfunction.

“The crisis was not caused by the winter weather,” said an official of an American nongovernmental organization, who spoke on condition of anonymity because he was not authorized to speak to the news media. “The crisis was triggered by the winter weather, but caused by chronic mismanagement.”