The quality of water supplies in the major city of Nanjing 1,500 kilometres downstream of the dam is also threatened, as pollutants and sediment become more concentrated in the shallower river. Water-treatment costs in the Jiangsu provincial capital are soaring as a result.

The People’s Daily website reported on Feb. 12 that the water level at the Xiaguan monitoring station near Nanjing had dropped to 2.29 metres – the lowest level recorded there since 1918 and almost 0.7 metres below the February average of 2.98 metres seen in recent years.

Abnormally low precipitation has been recorded in the upper reaches of the Yangtze in the past couple of months, and a similar shortfall has hit the Nanjing area in recent weeks.

But Nu Hongjun, an engineer with the Nanjing Water Resources Bureau, is also quoted as saying that the Three Gorges dam is contributing to the downstream drought, as water is held back in its huge reservoir for power generation.

Responding to an urgent appeal from the Yangtze Shipping Administration Bureau, the operators of the dam have agreed to release more water from the reservoir. The media reports say the Three Gorges Power Corp. has promised to provide an additional flow of 300 cubic metres per second, but they do not indicate the current rate of discharge. This information could also not be found on official Three Gorges project websites.

Already this month, eight boats have become stranded in the Nanjing section of the river, including a freighter loaded with 4,000 tonnes of cement powder, which ran aground in the main shipping channel. Other cities farther upstream – Huangshi, Jiujiang and Anqing – have reported a total of about two dozen stranded boats, Xinhua reported on Feb. 9.

The Yangtze shipping bureau is struggling to cope with the hazardous conditions on the river, sending out survey teams, work crews and 17 large dredgers to try and deepen the main channel. Boats of a certain size have also been banned from badly affected areas.

Leading environmental journalist Dai Qing [pictured right], a veteran campaigner against the Three Gorges dam, called the downstream water shortage “a danger sign.”

“The project authority has been forced to increase the amount of water released from the reservoir this time, but what happens if it is reluctant or even unable to do so next time?”

She wonders who will be held accountable for the losses suffered by the shipping industry when there is too little water for navigation downstream during the dry season – or too little water upstream during the flood season when the reservoir level is lowered for flood-control purposes.

“With all the competing demands on the river, from upstream and downstream users, who should have the final say on how Yangtze water resources are distributed and managed?” she asked. The current drought in the middle and lower reaches also highlights the folly of Beijing’s plan to draw water from the Yangtze and divert it to cities in the arid north, she said.

Ms. Dai recalled a comment made in 1971 by former premier Zhou Enlai. Reacting with alarm to problems that had emerged during construction of another big dam, Gezhouba, 40 km downstream of Three Gorges, he said: “The Yangtze is too important a waterway to permit anything to go wrong. If navigation is interrupted, then the dam should be blown up.”

Critics of the Three Gorges project have long warned of the scenario that is currently being played out on the Yangtze, as different sectors and regions clash over access to water resources.

Writing in Damming the Three Gorges, a critique published by Probe International in 1990 of the Canadian-funded feasibility study undertaken for the dam, geographers Shiu-hung Luk and Joseph Whitney said the study had not “dealt adequately with one of the most important issues: the inherent conflict associated with operating a multipurpose dam.”

The Three Gorges reservoir would have to be operated to meet the competing demands of power generation, flood control and navigation, but achieving optimum results for each function would require a different amount of water to be stored behind the dam, the authors wrote.

Prof. Whitney, then chairman of the University of Toronto geography department, and Prof. Luk, who taught in the department, concluded that it was not at all clear “what the impact of operating to serve peak electricity demands in the dry season would be on flows downstream of the Three Gorges dam and the Gezhouba reservoir. If, for example, the flows were too low, navigation depths would be insufficient and navigation would be impeded through this section.”

Kelly Haggart and Mu Lan, February 18, 2004