Reducing Run-off To Protect Lake Victoria

By Pius Sawa*WATER-UGANDA

GGABA, Uganda, Oct 24 (IPS/IFEJ) - The Ggaba landing site on Lake Victoria is the nearest wholesale fish market to the Ugandan capital, Kampala. More than 6,000 people live and work in this fishing community.

The water looks green and dirty from the quay. It smells like - well, like fish, or an abandoned, stagnant water pond. No one is willing to draw water from it for household use, and passengers coming and going from Ggaba to Lake Victoria's islands are keen not to step in the green water. The discoloration is as a result of too much algae on the water.

One fisherman, John Sentamu, is preparing his nets for a night on the water. The 66-year-old says all the algae has reduced the number of fish found near the lake shore. He says he no longer catches as much as he did five years ago. "I used to catch a full boat and my wife would sell the fish in the market each day. Our life was good. But now I can not even catch half a boatload."

What's going on?


"The fish, especially tilapia, have run away from the shore to the deeper water. No fish can stay in such dirty water. And my small boat cannot go further than ten miles." Sentamu compares his small craft to a large wooden vessel moored nearby. This larger boat consumes about eighty litres of diesel on trips of more than 130 kilometres miles into the lake, toward the islands in search of bigger fish. He says one needs more than $2,000 to buy a powerfully-engined boat like that. He, like most of Ggaba's fishermen, is confined to working closer to shore.

Other fishermen say tilapia, locally called ngege, lay eggs at the shallow end of the lake. But these days they're not laying; the implication is that the algal blooms have sent away the fish.

Biologist Lucas Ndawula, from National Fisheries Resources Research Institute (NAFIRRI), says tilapia habitat, including their breeding and nursery zones, is in shallow areas near the shore, so it is not true that algal blooms have forced them to migrate offshore into deep waters. Algal blooms are caused when there is an influx of nutrients, mainly nitrogen, that the algae feed on. They then reproduce in vast numbers causing a "bloom" in the lake, and using up a lot of dissolved oxygen in the water which makes it hard for fish and other aquatic life to survive. Ndawula says one of the results of overfertilisation is the development of excessive growth of algae in response to excessive nutrients in the water. "Because algae are food for many organisms and fish, the changes in algal composition and quantity manifest in long-term changes in the relative abundance of different organisms as has occurred in terms of the zooplankton community of Lake Victoria over time; 30 years or so."

The death of thousands of fish at gazetted fish breeding sites elsewhere on the lake in September and October has been linked to the algal blooms. The district fisheries officer at Jinja, Sarah Namulondo, says thousands of fish have died in the past three weeks and she is waiting for a report from the national Environmental Management Authority (NEMA) to determine the cause of the problem.

Mohammed Kityo, a fisherman at the Ggaba landing site, confirms that the fish are dying. He says on some days when he comes in the morning to collect the nets from water he finds some fish of various sized dead in the water. "It is true. The colour of this water must be the one killing the fish, because people stopped using poison to catch fish and now there are very strict laws to anybody found using chemicals to catch fish."

Fish stocks under pressure (photo tilapia)

As Kityo's comments reveal, the fish species in Lake Victoria have been under pressure from a variety of sources for some time - the Nile perch, a large predator introduced into the lake, ate up almost all of the endemic variety of tilapia, and alternative species had to be introduced. Artisanal fishing using illegal nets and pesticides has put further pressure on the most valuable commercial fish caught near the shore.

However the chairman of the Beach Management Unit at Ggaba landing site, Dirisa Walusimbi says the algal blooms are not permanent. He says there are seasons when they are constantly present, and seasons when they are rarely seen. He relates this to the amount of fish being caught. "This thing has been in the lake for many years. We have been seeing it in the entire life of our fishing. But there are times when it becomes too much especially when it rains." Part of what he says is in line with observations by researchers. Algal blooms are a result of too much nutrients getting into the lake, what NAFIRRI's Dr Ndawula describes as overfertilisation. "When the soil is laid bare by the removal of plants, natural or grown, rainfall sweeps large amounts of nutrient-laden soils into adjacent water body. This is the essence of soil erosion. Such nutrients, loaded in abnormal amounts lead to the phenomenon of overfertilisation and pollution," he says.

Many people around Kampala practice urban farming. They grow vegetables, bananas, potatoes, and rare cattle, pigs and poultry. The chemicals used and the run-off from the farms finds its way into the lake during rainy seasons.

The algal blooms at Ggaba and elsewhere are also linked to the burning of charcoal. Ndawula says too much burning of organic material also contributes to the fertilisation of the lake when the carbon goes in the air and comes down to the lake.

Dumping of industrial waste is another cause of overfertilisation and pollution of the lake. The Jinja district environmental officer, Ernest Nabihamba, says pollution has grown because of the unregulated dumping of waste in the lake, which leads to high concentration of ammonia that depletes the water of oxygen and suffocates the fish. The effects of the blooms are not limited to fishing. The National Water and Sewerage Corporation which supplies water to the city of Kampala is facing problems with its water treatment plant. Since the middle of September, most of Kampala has been on water rationing, apparently because the algal blooms have blocked the water turbines.

Warning's ignored

Ten years ago NAFIRRI warned that increased agriculture and growing industry around the lake led to increased in municipal waste and industrial effluent. The report warned that the fish stocks in the lake were at risk of being reduced by half. NAFIRRI says its warnings have not been heeded. "When industries are not treating or cleaning the effluent from their factories, there is a high chance that both nutrients and pollutants will end up in adjacent water bodies and cause pollution. Without going into names, all industries and factories that have no effluent treatment facilities may be polluting our water bodies. Uganda Breweries at Portbell is a good example (of a company) that has a treatment plant for its effluent," says Ndawula.

To mitigate the problem, NAFIRRI gazzetted four fish breeding sites on Lake Victoria to help boost the stocks which are reduced by algal blooms. But this cannot work if other measures are not put in place to reduce overfertilisation of the lake. NAFIRRI has released several reports advising government and the population on how to control the run-off to the lake. There are some signs that the Institute is being listened to. The Beach Management Unit at Ggaba has put in place by-laws to stop people releasing waste into the lake. The chair, Dirisa Walusimbi, says virtually all activity is prohibited around the swamps which are the main natural water filters. Car maintenance and washing bays which release engine oil and other chemicals are restricted within the lake area. The oil palm growers on Kalangala Island are now planting a leguminous cover crop to prevent fertilisers being washed into the lake. There is also a 200 meter buffer zone between the lake shore and the area under plantation to prevent erosion. And a 300 million euro aquatic weed control project between Egypt and Uganda has elevated part of the landing site to reduce pollution from neighbouring communities. The run-off from neighbourhoods will now be directed via a drainage channel into a swamp that will filter the water before it goes into the lake.

The measures to protect the lake at Ggaba are a step in the right direction. The hope is that it in concert with similar efforts around the lake, this will see the shores again becoming healthy enough for the tilapia to return in their previous numbers.   *This story is part of a series of features on sustainable development by IPS - Inter Press Service and IFEJ - International Federation of Environmental Journalists, for the Alliance of Communicators for Sustainable Development (www.complusalliance.org).

(END/2009)