Pollution of River Mara raises safety concerns about Lake Victoria waters

Wilderbeests crossing River Mara from Tanzania's Serengeti. [Robert Kiplagat, Standard]

Environmental experts have warned of dire consequences in the expansive Lake Victoria region if the pollution of Mara River is not contained.

A report released last week by a team of experts from the University of Dar es Salaam’s Department of Chemical Engineering and Minerals stated the river is highly polluted with decomposed invasive weeds and animal faeces.

On March 13, the Tanzanian Ministry of Environment formed a team of 11 scientists to investigate levels of contamination of water in the Mara River.

This was prompted after water in the river released a foul smell with traces of fish having been spotted dead on the shores of the river.

Findings indicated that water in the river was contaminated by animal faeces and the decomposed invasive weeds from Marasibora village in Rorya district down to Wegero in Butiama district following the heavy downpour.

The Mara River basin covers a surface of 13,504 sq km, of which about 65 per cent is located in Kenya and 35 per cent in Tanzania. From its sources in the Kenyan highlands, the river flows for about 395km, draining into Lake Victoria in Tanzania’s Mara region.

Now, concerns have been raised by a section of environmentalists saying this will cause more harm to the lake which is struggling with high levels of pollution.

Lake Basin Development Authority (LBDA) Agriculture and Natural Resource Chief Manager Mr Philip Oloo said high levels of pollution are choking the lake, threatening its entire ecosystem and the situation in Mara River makes it worse.

River Mara Water Resources Users Association (WRUA) chair Paul Rono demonstrates how to test for pollution. [Robert Kiplagat, Standard]

He observed the increasing pollution in Lake Victoria day by day risk of collapsing a multibillion fish industry and destruction of marine biodiversity. “Pollution in Mara River must be contained as it is increasing the levels of toxic substances in the lake, a concern to worry about,” Mr Oloo said.

The environmentalist noted that the lake’s condition is poor, evidenced by high nutrients accumulation, sediment, and blooming algae. 

“The levels of pollution in Lake Victoria is evident by increasing water hyacinths and occurrence of algae blooms on the lake with the hardest hit being the Winum Gulf part of the lake,” Mr Oloo said.

Data from the Kenya Marine and Fisheries Research Institute (KEMFRI) shows that as of January, the water hyacinth covered 951 hectares of the Lake.

According to KEMFRI assistant director Ms Chrisphine Nyamweya, the dilution levels into the lake from Mara River is low. However, he says it’s still a concern as the water from the river is contaminated.

“Water flowing from Mara River to the lake is contaminated with reduced level flowing into the lake as a result of dilution but it is still a concern,” Ms  Nyamweya noted.

Kericho sub-regional manager with Water and Resource Authority (WRA) Mr Chrispine Wekesa however said there was no cause for worry as the Kenyan part of the Mara river is safe.

“We are doing water monitoring and evaluation to see any changes in the water and advice the residents accordingly,” Mr Wekesa said.

He said it is important to reverse the levels of contamination in the water to protect the lake given that the Mara River flows in Lake Victoria and directly from the Tanzanian side.

Mr Patrick Odhiambo, an ecologist at Ecology Without Borders Organisation observed that pollution has made Lake Victoria’s waters unsafe.

“The fish and aquatic life is also not safe in most areas but that can be improved through control of pollution,” Mr Odhiambo said.

Hippopotamuses at the Mara River. [Wilberforce Okwiri, Standard]

Statistics from KEMFRI also show that species like Tilapia have shrunk by more than 50 per cent in the last decade but resilient Nile Perch is at 23 per cent.

Other small fish species are at 56 per cent, meaning they are the majority and being what is available has seen people staring at smaller fish sizes for the same price. In the last 50 years, Lake Victoria produced about 60,000 tonnes of Tilapia annually, but currently, it barely musters 20,000 tonnes.

The bigger Nile Perch has been resilient because one Nile Perch can produce 17 million eggs compared to Tilapia’s 300 eggs.

Nile Perch could have been about 340,000 tonnes a decade ago but has also steadily dropped to stand at about 200,000 tonnes, according to KEMFRI whose environmentalists cite wrong fishing practices as a threat to food security and livelihood to those who depend on the lake.

Mr Nyamweya explains that dwindling fish stock is a result of “more fishermen targeting the same fish. The lake is the same, we can’t expand it” and that other fish species besides Tilapia and Nile Perch have also been thinning.

 The fish stock is decreasing due to increased pollution in the lake, climate change and the use of illegal fishing gear. ?