During May and June 2007, a massive algae bloom broke out in Wuxi, Jiangsu province, provoking public panic and damaging local aquaculture businesses.

By late May, tap water in the city had developed an unpleasant odor. Experts later discovered the smell had been caused by contamination of the subterranean water supply, which was connected to Taihu Lake, by a type of blue-green algae called microcystis, which is highly toxic and dangerous to both plant and animal life.

Panic ensued, and local stores and supermarkets quickly ran out of bottled water. To quell public fears, the local government officials publicly drank boiled tap water to prove it was safe to drink, and also introduced measures to ensure the water was drinkable within a few days of the outbreak.

Blue-green algae can often be seen in rivers, lakes and other areas of high humidity. It severely reduces water quality, causes discoloration, raises the level of toxins and depletes the amount of oxygen in the water, endangering a wide range of aquatic life forms.

Leading research institutes and universities, including the Chinese Academy of Sciences, the Chinese Environmental Sciences Research Academy and Tsinghua University, attributed the bacteria's rapid rate of reproduction to the high concentrations of nutrients in the water.

Wuxi, about 120 kilometers from Shanghai, has long been famous as a hotbed of small - and medium-sized enterprises, and in the 1990s, large numbers of foreign-invested businesses started operations around the lake.

A lack of pollution-control facilities and poor supervision allowed lakeside businesses to discharge untreated wastewater directly into the lake - providing extra nutrients for the algae - which was later identified as a major contributory factor in the outbreak. In response, local authorities imposed a series of measures to clean the water and provide long-term pollution control.