Chinese weather experts are predicting more rainfall than usual this year, which could cause severe floods in the Yangtze Valley. The Beijing-based State Meteorological Bureau says precipitation in the Dongting and Poyang lake areas downstream of the dam is likely to be 20-per-cent greater than normal this summer.

People’s Daily ascribed the "high possibility of massive rainfall in the Yangtze’s middle and lower reaches … mainly to the influence of El Nino."

One of the worst Yangtze flood years of the past century occurred in 1998, when more than 3,000 people died. Officials are keeping an anxious eye on water levels this year, which in some areas have been similar to those recorded in 1998. Scores of people have already died in storms and floods that have hit southern China since mid-May.

Li Yongan, vice-manager of the Three Gorges Project Development Corp., has stressed the importance of being well prepared for the coming floods, which will put immense pressure on the dam for the first time. Meeting the flood-management challenge will help ensure that the goal of generating 5.5 billion kWh of hydropower this year is met, he added.

Since the temporary shiplock at the Three Gorges project was taken out of operation on April 10, the flow of water through the dam has relied entirely on 23 outlets at the bottom of the dam and 22 surface sluice gates. If things go according to plan, these structures will be closed June 1, and the reservoir water level will rise by less than five metres a day, until the 135-metre level is reached on June 15. But if floodwater coming from upstream areas is more abundant than usual, the 135-metre level will be reached sooner than planned and the sluice gates will be pressed into service to discharge the excess water.

Meanwhile, the World Health Organization has warned that the summer floods could cause sewage systems to overflow, complicating China’s fight against severe acute respiratory syndrome (SARS).

"We see this as a potential threat, something to beware of," said Bob Dietz, a WHO spokesman in Beijing. "SARS could rear up again."

Mr. Dietz saw no way of preventing the problem. "You can’t stop flooding and there’s nothing that can be done to improve sewage systems at such a short order," he said.

While the SARS virus is not thought to be transmitted by water, it does appear to survive for days in human waste. Hundreds of residents of the Amoy Gardens apartment complex in Hong Kong contracted SARS in March and April after a malfunctioning sewage system spread the virus around the building.

Thousands of rural residents could face a similar threat during China’s flood season, when water laced with sewage can inundate homes and contaminate drinking water.

The WHO warning, which referred to natural, annual floods, also raises an unanticipated concern about the imminent manmade flooding of the Three Gorges area.

Thousands of public toilets were among the areas that had to be cleaned up before the huge reservoir begins to form behind the Three Gorges dam. According to a survey conducted in the early 1990s by Chongqing’s Centre for Disease Control and Prevention, the reservoir area contains 300,000 square metres of public toilets and 1,500 slaughterhouses.

With China’s SARS crisis underscoring the importance of a thorough scrubbing of the reservoir bed, the South China Morning Post reported in March that the cleanup campaign was faltering. The Hong Kong newspaper quoted State Environmental Protection Administration (SEPA) official Xie Zhenhua as saying that water pollution in the dam region was higher than expected, that many industrial wastewater treatment projects were not meeting targets, and efforts to remove garbage from the area were moving slowly.

And just two weeks ago, SEPA issued a directive calling on officials in the Three Gorges area to redouble their efforts to remove all possible sources of infectious disease, including SARS, before the reservoir begins storing water this Sunday.