The sun has just risen and its rays are cast on the waters of the Shire River. The grass is still wet with a mixture of dew and the January rains that turn all vegetation on the river banks green. It is just another day in Traditional Authority Liwonde, Machinga district where a section of the river Shire flows.

Standing on the left side of the Shire river bank, my eyes are attracted to the Shire River that is sandwiched between trees and vegetation up the stream. At this point, the Shire River measures 50 Meters in width. About two kilometers up the stream, all I can see is green vegetation and the beams of light from the sun reflected in the water.

Then in an instant, my brain registers a movement; some green land seems to be moving downstream. As it gets closer, I can see that it is moving very fast. Following the rains, the current is very fast on the Shire River and the green land is fast being carried downstream. Faster and faster, it sails towards the Liwonde barrage, determined to reach its destination.

Finally, the green moving island sails past me and attaches itself to another green island on the river, a hundred Meters from the Liwonde Barrage. The island measures 50 M by 8M; this can be compared to a size of half a football ground. The green moving land is called an island of weeds.

According to people of Mpilisi village in traditional Authority Liwonde, the floating islands have now become a common site.’’ In the 1970s weeds were seen once in a while but these days weeds are seen more often and mostly in the lagoons’’ said Abiya Alibi.

In 2003, ESCOM management formed a task force which was named Shire River Management, to mitigate the weed problem at Kapichira, Tedzani and Nkula power stations. The weed problem resulted in government handing over the operations of the Kamuzu Barrage to ESCOM in 2004. Commissioned in 1965, the Kamuzu barrage has fourteen radial gates mainly used to regulate water flows to power stations and to control floods. The gates now have to be operated more frequently in order to flush the accumulated weeds at the gates.

The assistant operation engineer at the Liwonde Weed Management and Barrage Operations section Gerald Mbiro, says traces of floating weeds were noticed in the Shire River in the late 1990’s and the size of the floating weeds varies between 50M by 8M to a single plant of a Water Hyacinth (Namasupuni).”We are not sure where these weeds come from, perhaps from lagoons along the upper section” Mbiro says. The weed islands are a mixture of plants and grasses which include water lilies, water hyacinth, reeds, papyrus and others.
The floating weeds may look innocent when they float on the water, but when they find their way further down to power generating plants such as Nkula, Tedzani and Kapichira, they affect power generation. In 2001, ESCOM lost Tedzani 1 and 11 machines due to floods and weeds. The two plants have a total generating capacity of 40 Megawatts.

ESCOM has since 2004 been using a number of ways to harvest the weeds. The Corporation started by engaging local fishermen to manually remove the weeds with canoes and panga knives. The method was not effective as the amount of weeds accumulating kept increasing. Over the years, the Corporation has used semi mechanical harvesting where the Malawi Lake services were engaged using motorized boats and a grab crane to trap and harvest the weeds. The method was not effective because the weed islands were too big to trap.

In 2005, ESCOM under the weed management and barrage operations section started deploying mechanical harvesting methods .The section uses one harvester, one weed cutter, a service boat and an oil spill boom to manage the weeds at the barrage. Big islands of weeds are first stopped by a boom that prevents them from floating further down the stream. The islands of weeds are chopped into pieces before a harvester separates them from the river. The harvester then conveys the weeds in a truck at the river bank.

In 2006, ESCOM harvested 4,623 tones and 22,876 tones of weeds were harvested in 2007. During the peak season which starts in November and ends in May every year, an average of 120 tones of weeds are harvested every day.

After harvesting, the weeds are dumped in Machinga forest which is eleven kilometers South of Liwonde town assembly. Most of these weeds are burnt by bush fires in the forest. Some are collected by villagers and are being used by the communities to make compost manure and animal feed.

Though efforts are being made to remove the weeds at the barrage, some still find their way to the power plants and cause power generation problems. It is clear that there is need to find sustainable alternative solutions which should include managing the weed problems at the source and improved natural resources management in priority catchments within the middle and upper Shire River.

Unlike in the past, the floating weeds cannot be ignored. It is time to know their source and the activities that are contributing to their existence as well as any beneficial use they are to the communities. Otherwise, Malawi which mainly relies on the Shire River for energy production will continue paying greatly through high cost of weed management on  Shire River.