The east China waterway, formerly a scenic attraction famous for its aquatic life, has been badly contaminated by industrial, agricultural and domestic wastes.

An outbreak of algae on Taihu last month fouled the drinking water supply for more than two million residents of the lakeside city Wuxi. The water was so bad that the taps were shut down for two weeks until purification efforts could be completed.

Under a plan released on Saturday, the province set a goal to stop all lake algae outbreaks within five years. A key measure involves closing 2,150 factories engaged in chemical making, metallurgy, printing, dyeing, paper production and electroplating.

Those factories are being urged to switch to more environmentally friendly industries, such as high-tech and services.

Meanwhile, all cities and towns around the lake are required to substantially reduce sewage discharges into the waterway by setting up additional treatment facilities for industrial and residential wastes and upgrading the capacity of existing plants.

Provincial officials also said they intend to ban the use of detergents that contain phosphorus, one of the key chemicals responsible for the algae bloom on the lake.

To curb contamination caused by agricultural runoff, farm communities around the lake will be ordered to decrease the use of pesticide by 30 percent and nitrogen-based fertilizers by 20 per cent in the next three years. Aquatic production in the lake will also be drastically reduced.

The cleanup plan envisions an "ecological belt" one to 10 kilometers wide around the lake to restore its natural balance and former beauty.

Province Party Secretary Li Yuanchao pledged to adopt the "strictest rules" in the country to fight environmental pollution.

He urged governments at all levels to allocate more funding for environmental protection projects and strive for "green" economic growth.

The province will adopt a strict environmental evaluation system in approving new projects and will stop issuing licenses to businesses that use obsolete technologies and equipment or cause serious pollution.

Jiangsu also raised pollution discharge fees beginning this month.

One of the most densely populated regions in China, Taihu Lake receives 56 billion tons of sewage each year.

At the same time, about 30 million people rely on Taihu, China's third-largest freshwater lake, for drinking water, including nine cities in the provinces of Jiangsu and Zhejiang as well as Shanghai.

During an inspection tour of Wuxi on June 30, Premier Wen Jiabao called on all local governments to tackle algae outbreaks that foul the country's freshwater lakes. He urged officials to consider environmental management of the lakes as a state project.

"We should tackle the problem with a scientific approach, good leadership and high standards and confidence," Wen said.

Algae outbreaks have also been reported in Chaohu Lake in central China's Anhui Province and Dianchi Lake in Yunnan Province in the south.