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Zambia Story

Protecting Lake Victoria's waters
and East Africa's agricultural base


While participating in Globe 2002 Business and Environment Conference in Vancouver this March, we had the honor of meeting Jane Dauffenbach, President of Aquarius Systems of North Prairie, Wisconsin, a company that has been making great strides in the area of long-range conservation and cleanup. Several decades ago, when Jane's father was CEO, I wrote and produced a documentary video that featured weed harvesting in one of its sequences. It was for the hydroelectric power utilities of Alberta, Canada. We were pleased to learn that this same company is involved in keeping Africa's largest lake free of a potentially destructive weed. Thanks to Jane, we are proud to present the following information, which may help other African countries tackle and solve some of their own problems.

The Challenge: Lake Victoria is the second largest freshwater lake in the world. It covers nearly 27,000 square miles, an area roughly the same size as the Central American country of Costa Rica. Bordered by Kenya,Tanzania, and Uganda, the lake serves as a valuable resource to the region providing food, potable water, hydroelectric power, and transportation. Water hyacinth (Eichhornia Crassipes) is a free floating water plant that is native to South America. It can vary in size from a few inches tall to over three feet. This plant has blue-green leaves, thick stalks and a showy purple or lavender flower. It thrives in tropical regions and in waters that are high in nutrients.

Lake Victoria and surrounding area

The main way water hyacinth reproduces is for a mother plant to send out a stalk which grows a daughter plant, which matures and sends out another daughter plant, and so on. It is common to find several generations among one stand of hyacinths, as the plants often remain entangled in a large mass. Hyacinths can also reproduce through seed, but the seeds must germinate in very shallow, muddy areas. A seed dropped in relatively deep water is unlikely to ever grow. Rarer still is the possibility of the hyacinth to regenerate from a plant fragment. It may be able to do so, but it would take ideal conditions and several months for a whole plant to form.

Aquarius did the water hyacinth eradication work on Kenyan Lake Victoria, and has a base in Kisumu. We have been visiting other countries in sub-Saharan Africa as well, surveying their lakes, rivers, reservoirs and dams, and putting on seminars and making recommendations upon request.

We have a website on the Kenya project itself: We actually completed the 1500 hectare project two years ago, in April 2000. The attached article will tell the rest of the story that you don't find on the website.

The weed growth has greatly inhibited transportation and fishing where ever it has struck. We saw bays where the weed came in and parked itself for several years. There were wooden fishing boats that lay rotting on the shoreline where they were last beached - - - the day before the green iceberg arrived six or more years ago.

The extraordinary weed growth is merely a symptom of a more serious illness, which is the external nutrient loading from the surrounding watershed in the form of Point and Non point source pollution.

Point source pollution can be specifically identified, like untreated sewerage, fish processing waste, and other industrial waste that is discharged directly into the lake. You will often see a pipe or drain from which these contaminants are entering the lake.

Non point source pollution includes agricultural runoff, sediment loading resulting from deforestation or overgrazing, etc. It is generally pollution that is brought in after a rainfall. The lake is like a big sink, and the non point source pollution drains into it from the surrounding watershed. These point and non point source pollutants are what must be ultimately addressed in the overall lake management plans.

The lovely water hyacinth is an exotic plant hailing from Brazil, and was most certainly introduced years ago as an ornamental. But being an exotic plant, it took advantage of the wide open nutrient rich spaces available in the lake, and has it flourished.

There are three methods to control water hyacinth: Chemical, Biological and Mechanical. Aquatic herbicides can be applied to the surface of the plants and may succeed in killing the vegetation. However, there have been many valid environmental concerns raised with introducing a chemicals into the waterway, because it supports a diverse fishery and serves as a water supply for both humans and animals. In the bigger picture, most countries around the world are now shying away from and banning the use of aquatic herbicides.

Biological control includes the introduction various insects including two types of weevils that feed exclusively on water hyacinth. However, this is not necessarily lethal to the plant (the bugs don't really kill their host since they need the plants to survive to support their future offspring). Instead, weevils stress the mature plants, and help keep new growth in check by slowing it down. Weevils are relatively inexpensive to introduce to a waterway, but the program should be managed by professionals. Other biological control methods are under study and may include introducing a pathogen that will exclusively attack water hyacinth, in the form of a disease or fungus.

Finally, mechanical control involves using special machines to chop the plant to destroy it, or the harvesting of the plant to remove it from the waterway, or a combination of both techniques. Which mechanical method is used is dependent on the particular circumstances. Mechanical control is more costly and slower than herbicide use, but it is selective, effective, and considered environmentally friendly.

It is practical and desirable to develop a management plan that incorporates one, two, or all of the above control methods, depending on the situation. For example, weevils can be introduced for long term control, while mechanical chopping and/or harvesting is used to provide immediate relief so that the lake is accessible for transportation and fishing.

According to Jane Dauffenbach, "Indeed we had the experience of using our Swamp Devils in Kisumu as ice breakers, where we drove ahead of the police boat or ferry that needed to leave the Port. We blazed open a trail through the weeds so that the boats could navigate to the open water."

Good Works from Bad Weeds
Next: Creative products and furniture made with the residue from harvesting hyacinth on Lake Victoria.