New Delhi, May 5 : The discovery of blue-green algae in Chaohu Lake, which is China’s fifth largest body of fresh water, has threatened drinking water for about 320,000 people.

According to environmental officials in China, the lake, which is located in the Anhui Province, has been severely polluted in recent months, as a result of the algae.

Chaohu Lake, which covers 13,000 square kilometers and supplies drinking water to about 320,000 people on its eastern banks, became increasingly polluted after nearby cities industrialized and the wetland was destroyed.

From June to August last year, nutrient runoffs and other pollutants caused blue-green algae blooms in Taihu, Chaohu and Dianchi lakes, endangering water supplies for nearby cities and threatening aquatic life.

The worst algae outbreak was in the eastern Taihu Lake, the country’s third largest freshwater lake, and it rendered tap water undrinkable for about 10 days for more than 1 million people in Wuxi, Jiangsu Province.

Blue-green algae occurs naturally in rivers, lakes, damp soil, tree trunks and hot springs.

Following a long stretch of hot, dry weather, patches of algae were found in the western part of the lake, and traces of algae also cropped up in the eastern part, according to Xiao Pu of the Anhui environmental protection bureau.

Xiao has attributed the situation to the heavy snowfalls early this year.

“When the snow melted, the water carried fertilizers and other nutrient runoffs to the lake, bringing the volume of nitrogen and phosphorus to a higher level,” he said.

“Normally, algae need a proper proportion of nitrogen and phosphorus, continuous temperatures above 25 degrees centigrade and strong sunlight for at least three days to thrive,” Xiao explained.

“Although there are no signs of a massive bloom of algae in the lake, current conditions are conducive to algae growth,” he added.

In a bid to overcome the situation, the provincial environmental authority has ordered local environmental officials to enhance monitoring of the lake and plan for alternative water supplies. (ANI)