By David Stanway
SHANGHAI (Reuters) - Chinese conservationists have slated a plan to dam a key flood outlet for the Yangtze river, the Poyang lake, fearing a hammer blow for an already fragile ecosystem, a rest area for migratory birds and home of the endangered Yangtze river porpoise.
The outcry comes after the Jiangxi provincial government earlier this month revived a project aimed at regulating water flows on the Poyang lake, China's largest freshwater lake, which is increasingly prone to drought in winter.
A Shanghai-based non-government environmental group called Free Birds said in an open letter to the Jiangxi government last week that the project's approval would be "extremely irresponsible".
It accused Jiangxi of sneaking the project through without proper consultation, and said it defied a plan led by President Xi Jinping to better protect the ecology of the Yangtze, which supplies water to 40% of China's population.
Under revised Jiangxi government plans, a sluice gate will be built spanning 3 kilometres between the lake and the Yangtze river, aimed at gaining control over water levels and alleviating drought.
A hydropower plant first proposed around a decade ago has been ditched, but critics say the sluice gate will still break the natural link between Poyang and the Yangtze.
The Free Birds group said the Jiangxi government should look at the real reasons for the decline in the Poyang's water levels, including sand mining and the holding back of water by giant reservoirs like the Three Gorges.
The Jiangxi provincial government didn't immediately respond to a fax seeking comment.
Poyang, once described by President Xi as a vital "kidney" filtering China's water supplies, has long served as a flood outlet for the volatile Yangtze, and its waters traditionally drain back into the river during the winter.
But winter droughts have worsened in recent years - the Poyang all but disappears, depriving farmers of irrigation and further shrinking the habitats of migratory birds and the Yangtze river porpoise.
Speaking at a seminar on Saturday, Wang Hao, professor with the China Academy of Engineering, backed the project, saying lake conditions - caused partly by upstream hydropower - would not be easily reversed, but the project could at least improve local farming.
He also said the project's design did include specific features aimed at minimising habitat disruptions, adding that "the benefits will outweigh the disadvantages".
But fellow academics said the long-term challenges facing the Poyang lake were too complex to be solved by a single project, and further disruption to water flows could make things worse.
"The decline in the water levels of the Poyang lake is caused by many reasons, but generally speaking it is mainly the impact of engineering, including the Three Gorges Dam," said Lu Shanlong, researcher with the China Academy of Sciences' Aerospace Information Research Institute.
"The best way to solve it should be to optimise the way it is currently engineered, and not add even more engineering," he said.