Officials from east China's Jiangxi have been pushing for support of a water project at the mouth of China's largest freshwater lake Poyang, but the potential impact of the project is still strongly disputed.

On the sidelines of parliament's annual session, officials and lawmakers from the province have been talking to media and meeting with central government departments to rally support.

"It's imperative to start the Poyang Lake water conserve project under the current circumstances," said Yao Mugen, a deputy to the National People's Congress (NPC) and vice governor of Jiangxi, where the lake is located, referring to the preparatory work the province has done over the years.

The planned water conservancy project at Poyang Lake has been described vaguely by the Jiangxi provincial government as a "multi-purpose program" that will improve the area's ecology, irrigation and water supply, while helping schistosomiasis prevention and boost the development of shipping, tourism and fishing industries.

Local officials are reluctant to call the project "a dam," but rather describe it as "a sluice gate" at the mouth of Poyang where water from the lake flows into the Yangtze.

"In fact, the water conservancy project at Poyang Lake is a sluice gate, not a dam," said Hu Zhenpeng, who is also a deputy to the NPC, China's top legislature. "It will only help maintain water levels during the drought season but won't disturb the high water flows during the flood season."

Those who question the project said the water project could have a negative impact, as building a dam on the lake will cut off its link with the Yangtze, threaten the ecological system and might worsen droughts during the low-water season and destroy wetlands.

Damming the Poyang from the Yangtze river has also raised concerns that the project may affect water supply to the downstream of the river, particularly during drought seasons.

"The dam and its hydropower stations will bring disastrous damage to Poyang's ecology and wildlife," said Cao Wenxuan, a biologist with the Chinese Academy of Sciences.

Cao and 14 other academicians submitted a report to the State Council, or China's cabinet, opposing the proposal to construct a dam at the lake.

Cao said he remains doubtful even after the provincial government's latest plan to have more sluice gates, saying the gates would still narrow the lake's mouth by one-third and result in rapid water flows that might disrupt the activities of fish whose habitat areas are located nearby.

Yao said Jiangxi has, as part of the preparatory efforts for the proposed project, thoroughly analyzed the project's potential impact on wetlands, migratory birds, spawning migration of fish, the aquatic environmental pollution and silt deposition.

Poyang Lake is a key water supply source for about 1 million people and a natural habitat for numerous migratory birds and aquatic species.

Over the past years, reduced rainfall, rampant sand dredging, and the building of about 29 dams at the upstream of the Yangtze, have caused the size of Poyang Lake to shrink, from 4,000 sq kms at its peak to 200 sq kms in January, with water levels plunging to a six-decade low of 7.93 meters.

Hu said the key to protecting the lake is to keep its water above certain levels to stop the degradation of wetland and maintain a sound ecological environment, which can be ensured after the completion of the water project.

Poyang Lake is considered a major destination of migratory birds in the region, attracting more than 500,000 birds of 52 species, such as endangered hooded cranes and white-naped cranes, in the winter of 2011.

The lake is also home for near-extinct Yangtze River dolphins and many other endangered species. Some environmentalists estimate that about 70 percent of Poyang's fishery resources have vanished over the last three decades.

"Any project has its negative impact, so we need to weigh the pros and cons," said Sun Xiaoshan, an NPC deputy from Jiangxi province and head of the provincial department of water resources.

Sun said he believed the negative impact of the Poyang water project could be minimized.

A joint environmental review report by six research institutions in 2011said "some negative impact" on the ecological environment caused by the project could be "lowered or mitigated" through scientific measures.

The institutions included Poyang China Institute of Water Resources and Hydropower Research, Chinese Research Academy of Environmental Sciences, Institute of Geographical Sciences and Natural Resources Research and Institute of Hydrobiology both with the Chinese Academy of Sciences.

In February 2012, the Water Resources Planning and Design Academy was authorized by the Ministry of Water Resources to approve in principle the proposal to build the water project in Poyang Lake.

Still subject to approval from the National People's Congress and the central government, the project is not on the agenda of the parliament's annual session, which is slated to close on Wednesday.