Report unveils origin of pollution in Lake Victoria Basin
Monday, September 01, 2003
The East African Standard (Nairobi, Kenya) Ken Odondi
The main causes of pollution in Lake Victoria are municipal sewerage outlets, industrial and mining activities. The Executive Director of Osienala (Friends of Lake Victoria), a Non-Governmental Organisation, Dr Obiero Ong'ang'a, says that this is so because sewerage treatment plants in municipalities bordering the lake do not work.
Raw sewerage is discharged into the water system, poisoning aquatic life and also endangering the lives of human beings. He says that four years ago, Osienala's report on the state of Lake Victoria Basin painted a terrifying picture of pollution.
The study indicated that Kisumu Municipal Council has been treating the urban waste for over a decade. It also indicated that sugar industries in Western Kenya were among the heaviest polluters. Muhoroni Sugar Factory and its molasses-producing counterpart, Agrochemical and Foods Company Limited, for instance, are among the worst industrial polluters.
Effluent released from Agrochemical and Food Company had biological oxygen demand (BOD) of 95,000 mgs/litre as opposed to the World Health Organisation's (WHO) recommended level of 100 mgs/litre. "The raw waste is dumped into the lake, especially the untreated human waste from the blocked sewerage system," says Ong'ang'a.
He points out that there are similar cases in the urban centres surrounding the lake like Kendu Bay, Homa Bay, Mbita, Muhuru and Asembo Bay. He claims that like many other factories, they had taken advantage of weak environmental laws and opted to pay ridiculously small fines rather than improve their treatment plants.
Ong'ang'a says, however, that through Osienala's campaigns, the companies have been forced to install new treatment works and are gradually reducing the toxicity levels of their effluents, but still not to the required standards. He further points out that garages and petrol stations are some of the sources of oil and grease pollutants in the region.
Specific sources include the Kenya Railways depot in Kisumu, oil companies, steamers and motorised boats plying Lake Victoria. He says concentrated septic tanks and pit latrines in the major urban centres also pollute the lake through underground filtration systems. "There are also metals discharged by factories as well as waste papers, matches and batteries. Others include tannery wastes mostly chromium, fish particles and wastes from the fish processing and filleting companies and corrosive chemicals from the hospitals and pharmaceutical wastes," he says.
He says the studies also indicate that the high phosphorous and nitrogen concentrates currently choking the lake are attributed to several non-point sources. The most important of these have been identified as coming from agriculture, livestock and industrial effluents.
Most of these activities, he says, use large amounts of synthetic compounds including fertilisers. Estimates show that up to 22,000 tonnes of phosphorous are loaded into the aquatic ecosystems of Lake Victoria basin annually. "Although animal manure and domestic wastes contribute about 3000 tonnes and 132 tonnes of the total, respectively, their nitrogen inputs are estimated at over 40,000 tonnes per year," notes Ong'ang'a.
He says this represents more than three times of pollutants from synthetic fertilisers. Ong'ang'a says due to the high population growth rate, there has been the need to intensify agricultural practices, which have, as a result, had negative impact on the environment.
He says because of deforestation, which aims at increasing agricultural land, there has been increased soil erosion and high loads of silt and nutrients being transported through the rivers into the lake. The wetlands bordering the lake have been converted into either industrial or agricultural land and, therefore, have been unable to act as natural filters for nutrients and silt.