Water rose to the maximum level at China's Three Gorges Dam yesterday, driving electricityoutput to full capacity at the world's largest hydropower plant for the first time since it began operating two years ago, its operator said.

This marks the culmination of the mammoth US$23 billionproject on the upper reaches of China's longest river, the Yangtze, touted by the government as the best way to end centuries of floods along the river basin and to provide energy to fuel the country's economic boom.

But some critics said the dam would cause environmental problems and its construction displaced more than 1.4 million people. Some geologists also warn that raising the water level of the vast reservoir carries a heightened risk of landslides, earthquakes and prolonged damage to the river's ecology.

Construction of the 660-kilometer-long dam began in 1993 and it was finished in 2006.

Its water level hit its peak height of 175 meters at 9am yesterday, according to projectoperator, the China Three Gorges Project Corp. The previous record was 172.8 meters set in 2008, the year the generators began operating.

Company Chairman Cao Guangjing called it a "historical milestone." He said annual power generation will reach 84.7 billion kilowatt hours which would "enable the project to fulfil its functions of flood control, power generation, navigation and water diversion to the full."

To reach that level, dam officials began holding back water in September. The water level will be maintained at the current height for about two months and then be allowed to drop, the Xinhua news agency said. In the future, the water level will be kept between 145 meters and 175 meters, depending on flood control needs.

But that could carry risks.

Last year, the Chinese investigative magazine Caijing revealed a government report which warned that rising water levels were increasing landslide risks by reviving old landslide fissures as the soil around the dam became more saturated and unsettled.

The report cited a pre-flood inspection report by local officials that identified nearly 700 areas vulnerable to geological damage, 587 of them possible landslide spots.

When reservoir officials attempted to raise the water levels last fall, at least one town near Chongqing City had to evacuate dozens of residents after a 400-meter hairline crack appeared on slopes.

But hydrology expert Yan Echuan, part of an expert team hired by the government to assess geological risks of the project, said he doesn't believe that keeping the water at the maximum level poses an increased danger, as water levels have been as high as 172 meters in the past.

"Theoretically, there would be risks of landslides and even collapses," said Yan, a professor of hydrogeology at China University of Geosciences in Wuhan. "But it does not make much difference if the water level is raised two or three meters from 172 to 175 meters."

He said he was only aware of "one or two minor cases of earth-shifting" caused by the raised water level.

• yesterday [´jestədi] n.&ad.昨天；前不久 (初中英语单词)
• output [´autput] n.产品；产品；计算结果 (初中英语单词)
• capacity [kə´pæsiti] n.容量；智能；能力 (初中英语单词)
• operator [´ɔpəreitə] n.操作者；接线员 (初中英语单词)
• project [prə´dʒekt, ´prɔdʒekt] v.设计；投掷 n.计划 (初中英语单词)
• energy [´enədʒi] n.活力，精力；能力 (初中英语单词)
• construction [kən´strʌkʃən] n.建设；修建；结构 (初中英语单词)
• height [hait] n.高度；顶点；卓越 (初中英语单词)
• previous [´pri:viəs] a.先，前，以前的 (初中英语单词)
• annual [´ænjuəl] a.每年的 n.年刊 (初中英语单词)
• generation [,dʒenə´reiʃən] n.发生；世代；同龄人 (初中英语单词)
• fulfil [ful´fil] vt.履行；完成；执行 (初中英语单词)
• agency [´eidʒənsi] n.代理商；机构；代理 (初中英语单词)
• expert [´ekspə:t] n.&a.专家；内行 (初中英语单词)
• maximum [´mæksiməm] n.极点 a.最大的 (高中英语单词)
• electricity [i,lek´trisiti] n.电；电学；电流 (高中英语单词)
• billion [´biljən] num.万亿 (高中英语单词)
• navigation [,nævi´geiʃən] n.航行；航空；导航 (高中英语单词)
• inspection [in´spekʃən] n.检查；视察；参观 (高中英语单词)
• yangtze [´jæŋtsi:] n.长江 (英语四级单词)
• reservoir [´rezəvwɑ:] n.水库；蓄水池 (英语四级单词)
• diversion [dai´və:ʃən] n.转移；消遣 (英语四级单词)
• mammoth [´mæməθ] a.庞大的 (英语六级单词)
• holding [´həuldiŋ] n.保持，固定，存储 (英语六级单词)
• geological [dʒiə´lɔdʒikəl] a.地质学的 (英语六级单词)