The Three Gorges Dam, the world's largest hydropower plant, on the Yangtze River. Developers want to add a new facility on Zhongba island, Chongqing, but face resistance from environmental groups who fear the move could spell the end for several species of endangered fish. [Wen Zhenxiao/China Daily]

For an isolated community desperate for change in a Chinese municipality focused on economic success, a multi-billion yuan hydropower project is a dream come true.

For environmentalists, it heralds a further blow to the world-famous Yangtze River's delicate ecology.

Zhongba island in Banan district lies 40 km upstream from Chongqing and is inhabited by mostly poor vegetable farmers who must rely on ferries to bring supplies from towns on the shores of the Yangtze.

It is also the proposed site for the Xiaonanhai project, a 37-billion-yuan (US$5.4 billion) joint hydropower venture between the municipal government and the China Three Gorges Project Corp, which, if given the green light, will lead to thousands of residents on the island and in nearby villages being relocated to areas promising better job opportunities and living standards, as well as boost local energy supplies.

"There are rumors a dam will be built very soon and we will all be relocated to areas closer to downtown Chongqing. We're all looking forward to that," said a 70-year-old man surnamed Li, who has lived in nearby Tianming village for several decades. "I'm not sure where we will move to but I hope it is an urban area not far from Chongqing, which will mean better education prospects for my grandchildren.

"At the moment, it takes about two to three hours to get to the city by bus, which is very inconvenient. This will change everything."

The selection of Zhongba as the site for what would be the municipality's largest project in the 11th Five-Year Plan (2006-10), however, has proved less popular with scientists and environmental experts.

The intended location of the hydropower dam is in the experimental zone of the Upper Yangtze National Nature Reserve for Rare and Endangered Fish, said Guo Qiaoyu, the Yangtze River project manager for The Nature Conservancy, a non-governmental organization based in the United States.

"The dam will slow the water flow and create a giant reservoir that stretches deep into the reserve's buffer zone, threatening the survival of already very vulnerable fish species," he said.

The reserve stretches almost 300 km from the Xiangjiaba hydropower station in Yibin to Chongqing and is home to 189 types of aquatic animals, including more than 40 endangered species like the Chinese paddlefish, Dabry's sturgeon and Chinese suckerfish.

"This nature reserve is the last habitat for endangered fish species in the upper Yangtze, if not the whole of the river. Most of the river sections have already been exploited," explained Guo.

Cao Wenxuan, one of nation's top fish experts with the Chinese Academy of Science, added that the Xiaonanhai section was a vital ecological channel for some species.

"For those fish that migrate and breed along free-flowing rivers, such as the Chinese paddlefish, an uninterrupted migration channel is vital," he said. "Also, the eggs of certain species, like the elongated loach, can only hatch after floating a long distance. A dam at Xiaonanhai would completely block the migrant channels for these fish."

Sudden changes in water temperature, depth, oxygen content and current speed can alter a river's entire ecosystem, bringing challenges for the animal and plant life it supports.

The hydropower plant would generate 1,750 megawatts (mW), a fact that has been promoted by the municipal government as a solution to the region's power problems.

The largest city in southwestern China, Chongqing has seen persistent droughts and coal shortages threaten its energy supplies in recent years. Last spring several companies suffered blackouts as the city faced a 1.8-million-kW shortage of electricity.

Developers said the Xiaonanhai hydropower project would supply the power grid in Chongqing.

It has also been hailed as a golden opportunity to transform the lives of the 3,000 people still living on Zhongba island.

Banan has become a major district of Chongqing in recent years due to rapid economic growth and urban expansion, but not everyone has so far seen the benefit.

"Zhongba island is my hometown," said a contributor to an online forum at cqnews.net, a major news portal in Chongqing. "Life there is hard and I hope the villagers can move off the island as soon as possible."

The Xiaonanhai scheme was first put forward in 2006, with construction originally scheduled for 2007. It has since been in a state of limbo as China's Regulations on Nature Reserves does not allow such projects to be built in conservation areas.

The only way it can be approved is if the National Development and Reform Commission were to remove the protected status of the Zhongba site.

The setback has failed to deter the local authorities, however, and they are more determined than ever to get the Xiaonanhai scheme running.

Banan district government, which administrates the Xiaonanhai area, states on its website that it is "actively pushing forward the preparatory work" for the hydropower plant and has listed the project as one of this year's top priorities.

Meanwhile, bosses at China Three Gorges Project Corp have been busy selecting sites for their offices during construction of the dam, while public bidding for the equipment procurement started in March, according to official sources.

The most important efforts to clear the hurdles are arguably being done by Chongqing municipal government, where workers are fine-tuning plans to re-draw the boundaries of the reserve to remove the Xiaonanhai area, a source close to the authority told China Daily this week.

Several expert reviews to gauge the ecological impact of the hydropower project have already been commissioned by the Ministry of Agriculture, which is responsible for fisheries resources.

The first was in February and most experts came out opposed to the creation of a dam on environmental grounds. However, the same panel in May agreed that redefining the reserve boundaries would not ruin the aquatic habitat as long as channels were opened for fish to travel through the dam during construction.

"This conclusion effectively gives the green light to plans to re-draw the boundaries," said one of the experts, a researcher from the Chinese Academy of Fishery Sciences who asked to remain anonymous. "Once the dam site is no longer included in the nature reserve, building the dam will be legal."