Local environmental protection officials are playing down the discovery, insisting the algae is unlikely to develop into a bloom similar to that found in Taihu Lake last week, in neighboring Jiangsu Province.

"The algae is only in the western part of the lake and will not pollute the whole lake which measures about 750 square meters," said Zhang Zhiyuan, chief engineer of the provincial environmental protection bureau, without revealing the surface area of the lake affected by the algae.

But he admitted, "Theoretically speaking, the algae could spread unchecked. It is also impossible to eradicate it in the short term," Zhang admitted.

"But its growth is greatly influenced by weather. Thanks to the recent frequent rainfall that has diluted the lake, the algae has been notably curbed," he said.

However, environmental officials have been concerned enough to hold talks with the provincial water resources bureau about diverting water to the lake.

"A mere 700 million cubic meters of water is enough to prevent the algae from blooming," Zhang said.

The lake has suffered from high levels of nitrogen and phosphorus for years. The local environment agency is now closely monitoring water quality and says it will report anything unusual to the government.

"The eastern part of the lake, which is the source of drinking water for the neighboring Chaohu city, meets the country's drinking water standards," Zhang said. The city has a population of 320,000.

The Chaohu Lake experienced a blue-green algae bloom in July 2004 but it soon subsided after timely winds and rainfall.

Blue-green algae is a simple aquatic plant life that occurs naturally in rivers, lakes, damp soil, tree trunks, hot springs and snow.

"Bloom" is the common term used to describe an increase in the number of algal cells to a point where they can discolor the water, form scum, produce unpleasant tastes and odors, affect shellfish and fish populations or otherwise create a nuisance and seriously reduce the water quality.