A huge suburban wetland project is being planned to improve the quality of the city's tap water, local planning authorities have said.

The Qingpu district is planning to develop a 15-sq-km wetland around Dianshan Lake - source of about 30 percent of Shanghai's drinking water - to act as a filter for the water flowing into the city, the district's planning administration bureau said.

The district government will also encourage farmers living around the lake to farm "properly" to build a harmonious ecological system, an official surnamed Zhang said.

A 5.5-hectare forest of pond cypress - a water-preserving plant - will be grown along the wetland to improve the ecological situation, Zhang said.

He did not give a timetable for the project, as its details are yet to be finalized.

Local authorities have been keeping a close eye on the water quality in Dianshan Lake, following the blue-green algae boom in Tai Lake in neighboring Jiangsu Province last month. The district's environment monitoring station has done a thorough inspection and affirmed that no algae were found in Dianshan Lake.

Cui Liping, vice director of the Shanghai landscaping administration bureau (SLAB), said once completed the wetland project will significantly improve the water quality of Dianshan Lake.

"Shanghai's water source is being threatened, and we have to move quickly," Cui said.

"It's crucial to protect the wetlands, which are an integral part of our water resources."

Reserves of natural wetlands could rise from 25 percent to 30 percent by building nature reserves, Cui said.

"This wetland project is a part of that plan."

About 30 percent of the soil lands in Shanghai are wetlands, the SLAB said. The city's forest coverage was 11.63 percent in 2006, and its green space coverage 37.3 percent.

However, some people remain cautious about the city's water quality despite the government's efforts to reverse the effects of industrialization. Many visitors to Shanghai have also complained the tap water has a strong smell of bleach.

Mao Kejia, a local primary school teacher, said her family did not drink tap water, only purified water.

"It seems to me the water quality is getting worse and worse," she said.

"The problems are serious and it takes time before those pollution-tackling measures work."

(China Daily July 17, 2007)