Experts suspect chemical pollution after a foul smell emanated from the rive and dead fish were found floating on the water.
The Tanzania government has banned the usage of Mara River water for domestic use in four villages—Kirumi, Kwibuse, Marasibora and Ryamisanga—over suspected chemical pollution.
It has also banned fishing and any other use for the water as a team of experts investigates the cause of the pollution, which has resulted in the river having a foul smell and caused the death of fish.
The government instructed its Rural Water Supply Agency (RUWASA) in Mara region to look for alternative water supply for the affected villages.
Attention was drawn to the suspected pollution following reports last week of dead fish floating on the river.
Selemeni Jafo, the Minister of State in office of the Vice-President responsible for Union and Environmental matters, formed an 11-member committee to look into the source of the pollution.
Preliminary investigations show that a layer of oil was found on the water.
The river, which has its source in the Mau forests of Kenya drains into Lake Victoria at Musoma in Tanzania. It supports the lives of thousands of citizens and is part of the great Serengeti Ecosystem, which is connected to Maasai Mara of neighbouring Kenya.