Downstream impacts of mines on agriculture in Africa

Mining operations in Africa are expanding rapidly, creating negative externalities that remain poorly understood. In this paper, we provide causal evidence for the impact of water pollution from mines on downstream vegetation and agriculture across the continent. We exploit a natural experiment, where mines cause a discontinuity in water pollution along river networks, to compare vegetation health in upstream and downstream locations. We find that mines significantly reduce peak vegetation downstream by 1.3–1.5%, impairing the productivity of over 74,000 km 2 of croplands. These reductions correspond to annual losses of 91,000–205,000 tons of cereal crops in the immediate vicinity alone, with particularly severe effects in fertile regions and areas where gold mining predominates. Our findings highlight substantial externalities of mining and demonstrate an urgent need for oversight and regulation. • Assess causal impacts of mining-induced water pollution on agriculture and vegetation. • Exploit directed river networks for identification in a discontinuity design. • Mining in Africa reduces peak vegetation downstream by 1.3–1.5% • Over 74,000 km 2 of croplands are immediately affected and impacts may reach further. • Effects are strongest in gold mining areas and fertile agricultural regions.