Chambishi and the Kafue river (Zambian Copperbelt)

Copper mining at Chambishi began in 1963 under the Roan Selection Trust; the mine was nationalised in the 1970s, when the first tailings dam was built, and closed in 1987. With liberalisation, in 1998 China Non-Ferrous acquired 85% and reopened it. Its subsidiary Sino-Metals Leach Zambia, instead of building a new dam, had since 2019 been raising the walls of the old Musakashi tailings facility.

On 18 February 2025 the wall failed through internal erosion of the partition between the upper compartments. About 50 million litres of water containing heavy metals escaped, reaching the Mwambashi and then the Kafue and poisoning drinking water, irrigation and aquatic life. According to Wikipedia, citing the international press, fish died, crops along the banks were lost and the water supply of Kitwe, a city of about 700,000, was shut down; about 12 million people live in the Kafue basin.

It was not an isolated case: on 1 December 2023 a waste dump at the Nchanga mine in Chingola had slid, and on 19 January 2025 a leach pond at the Mimbula mine had failed. A study of the three incidents describes an environmental agency (ZEMA) perceived as ineffective and the absence of emergency plans shared with communities. On the old tailings dams of Kitwe and Mufulira, close to housing, the order of contamination relative to control soils is Cu > Co > Fe > Pb > Mn > Zn (Dusengemungu et al. 2022).