LUANDA, Angola—First the river turned red. Then dead fish floated to the surface by barrels. Then thousands of people started to get sick.
Now 12 people have died in the Democratic Republic of Congo in what researchers have called “an unprecedented environmental and human disaster” along the Kasai River, a southern tributary of the mighty Congo River.
Congolese government investigators and officials say the cause was a toxic leak upstream from Angola’s largest diamond mine, run by Catoca, a joint venture owned by Angolan state mining company Endiama, and Russian mining giant Alrosa.
The company admitted in a statement last month that there was a leak from its facility, but said it was just water and sand — nothing toxic.
In addition to the 12 fatalities, about 4,500 people became ill with diarrhea as a result of the pollution and a total of nearly a million people were affected, Eve Bazaiba, Congolese environment and sustainable development minister, said at a news conference on Thursday.
“It’s total destruction of ecosystems, especially aquatic biodiversity,” said Ms Bazaiba, who traveled to the region.
She said people living near the water noticed around July 26 that something strange was going on on the Tshikapa River, which flows north from Angola, where it is spelled Chicapa, and then flows into Congo and empties into the Kasai.
Initially, they thought that small-scale diamond mining was causing the problem, she said. But then, on July 31, the situation got worse.
“They noticed there were dead fish. Lots of dead fish – tons and tons, floating on the river,” Ms Bazaiba said.
A team sent to the area reported that two hippos had also died. “Everyone was panicking,” she said.
The government warned people not to eat the fish and took samples of the water for testing in laboratories in Kinshasa, Congo’s capital. A week later, the results came back. The water sample contained heavy metals – nickel and iron – and the pH level was not right, the minister said.
“It’s almost sour,” she said. “It sucks the oxygen out of the water. There is no more life.”
Researchers from the Congo Basin Water Resources Research Center at the University of Kinshasa called the pollution of the Kasai river basin “an unprecedented environmental and human disaster”. In a report released in mid-August, they said they had been monitoring the spill from its source in Angola’s Lunda Norte and Lunda Sul provinces since July 15, taking 15 days to reach the city of Tshikapa, at the confluence of the rivers Tshikapa and Kasai. It said two million people were at risk.
The immediate effects of the disaster so far, the report said, include water pollution, poisoning and loss of aquatic fauna and flora, waterborne diseases for riparian communities, disruption of fishing and navigation activities and lack of access to domestic water services.
It warned that pollution could spread downstream to the part of the river that flows through the sprawling metropolis of Kinshasa, one of Africa’s most populous.
Ms. Bazaiba said she hoped the Congo River’s voluminous water — second only to that of the Amazon — would reduce pollution by the time it reached the capital, adding that the water had begun to clear.
Meanwhile, the government is trying to figure out the source of the pollution, she said, but has to follow the procedure because it originated abroad.
“We don’t know exactly if it was an accident,” she said, “or if anything was known about it.”
Ms Bazaiba said the Angolan government and company acknowledged that the pollution came from the Catoca mine. She added that Congo would seek compensation on the polluter pays principle.
But the Angolan government has not said anything about it publicly. An official from the Ministry of Environment, Tourism and Culture, who was not authorized to speak publicly and spoke on condition of anonymity, said the ministry had not received any official information from the Congolese government. The official said the only information the ministry had was what it gathered from the media, and the investigation is still ongoing.
A company employee, who was not authorized to handle the case and spoke on condition of anonymity, denied that Catoca had confirmed the Congolese government’s claim that there had been a toxic spill.
The Catoca mine produces three quarters of Angola’s diamonds. One of the owners, the Russian company Alrosa, has been trying to increase sales in the United States in recent years.
In a statement last month, the company admitted that there had been a “rupture in the pipeline operating as a spillway”. But it said the only thing that had leaked into the river was a mixture of sand and water. It said an investigation had been carried out and that “the recorded situation did not pose a risk to the lives of the population.”
The company employee said Catoca did not use the heavy metals described by the Congolese minister.
“There can be no toxic materials coming from the Catoca mine because the mine doesn’t use such materials,” the worker said. “It was a concentration of sand and water, or to be clear, it was mud.”