Sanitation workers clean up water hyacinth in the Huangpu River yesterday. An outbreak of the floating weed is threatening the city's major waterways. 

 

An outbreak of the dreaded pest water hyacinth has spread to the Songpu Bridge area in Shanghai.

 

The floating weed was attracted to the spot by intake pipes for Shanghai's fresh water, sanitation officials said yesterday, adding that it was not yet out of control.

 

Water hyacinth has long been a headache for the public sanitation bureau. The plant clogs waterways, damages the environment, and kills fish by consuming all the oxygen in the water.

 

"The winter outbreak happened in mid-November this year, a little later than previous years," said Yu Hai, a bureau section chief. "We expect the outbreak to be over by early January."

 

Extra clean-up teams have been assigned to collect the plant, but so far there has been no adverse effects on Huangpu River navigation or the intake areas.

 

Yu said plants floated to the middle of the river near Songpu Bridge on Tuesday morning due to wind and tide. It is the first hyacinth infestation in the area.

 

In just two weeks to December 3, officials have collected more than 30,000 tons of the plant. The total amount of last year's winter outbreak was 46,000 tons.

 

The only way to deal with hyacinth is to collect and then bury them, Yu said, although some innovative methods have been tried in recent years.

 

One Shanghai company tried to make furniture out of the weeds but found them too thin.

 

Yu said a plan was floated to introduce an insect to eat the plant, but was shelved. Shanghai's climate proved unsuitable for the insect.

 

But a scheme to use the plant to generate electricity is still being considered.

 

The government made eradication of the plant a priority after a severe outbreak in 2002. Officials collected 120,000 tons of water hyacinths that year.

 

"Many ferries couldn't berth due to the heavy green plant," Yu said.

 

Autumn is the best season for hyacinths to grow. When mature they break into clusters and flow from the upper reaches of the Yangtze River to downtown Shanghai from October to late December or early January every year.

 

(Shanghai Daily December 7, 2006)