Water hyacinths endanger Malawi's main river

April 2002

U.S. Water News Online

SHIRE RIVER, Malawi -- Water hyacinths have been a problem in Lake Victoria.

A water weed is threatening to choke Malawi's largest river.

Water hyacinths have spread across a large section of the Shire River, according to a report by the country's Fisheries Department.

The Shire, an outlet of Lake Malawi which pours into the Zambezi River in Mozambique, is not only used for fishing and transport -- it is also a major source of hydro-electric power.

Fisheries Director Shaibu Mapila said that if left untackled, water hyacinths could destroy the Kamuzu Barrage, a dam operated by the Electricity Supply Corporation of Malawi (Escom). He said the weeds may even force the river to change course, displacing people along the way.

In an extreme scenario, the river could disappear entirely.

"I am not trying to be alarmist," he said, "but I know of the Kafue River which dried up in Zambia."

Environment Minister Harry Thomson, after inspecting the extent of the damage, suggested that Escom could flush the Kamuzu Barrage once a week to break concentration of the weed, as constant opening would make it flow down the river.

But Escom's senior engineer Dapper Chapalapata said this was not economically viable. Constantly opening the barrage would damage screens at power stations which may result in endless power interruptions.

Mr Chapalapata said Escom had already spent $1.5m to repair damage caused by the weeds.

The Fisheries Department survey blames the problem of water weeds on deforestation.

Environmentalists have ruled out chemically controlling the weed as an option, saying that would cause long-term ecological disaster. Other options include removing the weed manually or using machines.

In recent years the authorities in Kenya, Uganda, and Tanzanian have been battling against the spread of water hyacinths on Lake Victoria. There scientists have found that one of the most effective ways to control the weed has been the release of weevils that feed on hyacinths.


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