Heavy Metal Pollution in the Kafue River and the Way Forward

Background

The Kafue River is Zambia’s longest river lying wholly within the country and flows approximately 1,576 km. Its course starts near the border with the Democratic Republic of the Congo and runs south through the Copperbelt, then through Kafue National Park and the Itezhi-Tezhi reservoir, and east across the Kafue Flats to the Kafue Gorge, before it joins the Zambezi near Chirundu. The river sustains urban water supply, irrigated agriculture, fisheries, wildlife and hydroelectric power generation (Mbewe et al., 2020). Its upper reaches traverse one of Africa’s most intensively mined copper and cobalt regions. Press reports that about 60% of Zambia’s 20 million plus people live in the basin and depend on it for fishing, irrigation or industrial water (Kille & Zimba, 2025).

Potential sources of mining-related pollution along the river system can be grouped into four categories: (i) large-scale licensed mining and smelting operators; (ii) hydrometallurgical leach plants and processors; (iii) artisanal and unlicensed mining activities involving slag dumps and tailings; and (iv) legacy and abandoned tailings facilities. A World Bank appraisal attributes a “massive ‘environmental mortgage’” to “seventy years of mining operations, no formal mine closures, and a lack of concurrent rehabilitation”, and warns that “the risk of idle tailings dams (TDs) becoming eventual liability of the state has been increasing” (World Bank, 2016). The failure of the Sino-Metals Leach Zambia tailings dam at their Chambishi processing site, on 18 February 2025 demonstrated the consequences of an uncontrolled release of acidic leach residue into the Chambishi Stream, Mwambashi River and Kafue River (Zambia Environmental Management Agency [ZEMA], 2025a)6. The U.S. Embassy in Lusaka reported that the collapse released “50 million liters of acidic and toxic waste, including heavy metals” into “the Mwambashi stream and Kafue River ecosystem” (U.S. Embassy Lusaka, 2025a).

Priority metals and metalloids for investigation include copper, cobalt, lead, zinc, cadmium, arsenic, nickel, manganese and chromium, with mercury and uranium included where site-specific evidence supports their analysis. Acidic conditions can increase metal mobilisation. Heavy metal presence, concentrations and chemical forms should be established through validated laboratory analysis rather than assumed from mining activity alone.

Rationale

A major potential exposure pathway is river-sourced water supplied to communities in Kitwe, Kafue, Mazabuka and Lusaka. The Associated Press reports that the river supplies drinking water to about 5 million people, including in Lusaka (Kille & Zimba, 2025). In August 2025, the U.S. Embassy warned of “widespread contamination of water and soil by toxic heavy metals”, and restricted travel by U.S. government personnel to the affected towns (U.S. Embassy Lusaka, 2025a). The UK Foreign, Commonwealth & Development Office advised that “chemical waste containing heavy metals was released from a mine in Copperbelt Province” into the Chambishi Stream and the Mwambashi and Kafue Rivers, and that “boiling water does not remove heavy metal contaminants” (FCDO, 2026); other nations issued similar advice (Ministry of Foreign Affairs of the Czech Republic, 2025).

A second potential pathway is the food chain, through consumption of contaminated fish, crops and animal products from the river basin and its floodplains. The Kafue River basin supports livestock and diverse wildlife populations, including hippopotamuses, elephants, lions and Nile crocodiles. The Kafue Flats support the endemic Kafue lechwe and important wetland bird populations, including those associated with Lochinvar and Blue Lagoon National Parks. The basin’s fisheries sustain household food security and livelihoods (Mbewe et al., 2020). WWF Zambia values the ecosystem’s fisheries at an estimated US$26 million and states that wetland-derived products support approximately 6.1 million people (WWF Zambia, n.d.).  These connections between environmental contamination, animal health and human exposure justify a One Health approach.

Chronic exposure to toxic metals and metalloids may lead to renal damage, skeletal disorders, neurodevelopmental impairment in children, cardiovascular and respiratory disease, adverse reproductive outcomes and certain cancers, according to World Health Organization. The effects depend on the contaminant, its chemical form, dose, exposure route and duration. These established hazards do not demonstrate that such outcomes have occurred in Kafue basin communities. Metals can persist in sediments and accumulate in biological tissues, creating potential for prolonged exposure and risks to future generations.

Way forward

We propose a basin-wide longitudinal study of pollution in the river water and selected animal species, commencing with a two-year baseline establishment, from the headwaters to the confluence with the Zambezi near Chirundu. The study would use fixed, georeferenced sampling stations along the river and across its floodplains, including upstream reference sites and downstream locations sampled during wet and dry seasons. It would measure metal concentrations in water, sediment cores, fish and selected livestock and wildlife tissues, and link environmental findings to human biomonitoring and health surveillance in potentially exposed communities. Validated analytical methods and laboratory quality assurance would support comparisons across sites and sampling periods.

The study could establish an environmental baseline and support an early-warning system, evidence-based drinking-water and food-consumption advisories, implementation of polluter-pays obligations and financial assurance, and prioritization of remediation. Its findings could also inform tailings governance aligned with the Global Industry Standard on Tailings Management (United Nations Environment Programme [UNEP], 2020) and an open-data platform for public accountability. Protecting the Kafue River requires sustained collaboration among environmental, public health, veterinary, water, fisheries and mining institutions, alongside affected communities, to safeguard health, livelihoods and ecosystems for future generations.
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**RIS Contributors are researchers and practitioners writing for CCET's Research Intelligence Service.

References:

1.       Mbewe, J., Chivava, F., Mwale, C., Katiyo, L., Mwanza, O., Costanzo, S., and Kelsey, H. (2020). Lower Kafue River Basin Report Card Methodology Report. WWF Zambia and University of Maryland Center for Environmental Science. https://wwfafrica.awsassets.panda.org/downloads/lower_kbrc_methodology_report_2020_jm_sc_sc_cmk_sdc_ac.pdf

2.       United Nations Environment Programme (UNEP) (2020). Global Industry Standard on Tailings Management. https://www.unep.org/resources/report/global-industry-standard-tailings-management

3.       World Health Organization (WHO) (2019). Exposure to cadmium: a major public health concern. WHO/CED/PHE/EPE/19.4.3. https://tdr.who.int/home/our-work/global-engagement/WHO-CED-PHE-EPE-19-4-3

4.       World Health Organization (WHO) (2022). Arsenic. Fact sheet, 7 December 2022. https://www.who.int/news-room/fact-sheets/detail/arsenic

5.       World Health Organization (WHO) (2026). Lead poisoning. Fact sheet, 10 June 2026. https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health

6.       Zambia Environmental Management Agency (ZEMA) (2025a). Notice of a public disclosure meeting. 26 December 2025. https://www.zema.org.zm/notice-of-a-public-disclosure-meeting/

7.       Zambia Environmental Management Agency (ZEMA) (2025b). ZEMA receives Sino Metals pollution assessment report. 19 December 2025. https://www.zema.org.zm/zema-receives-sino-metals-pollution-assessment-report/

8.       U.S. Embassy Lusaka (2025a). Health alert: Copperbelt Province (Zambia), acute heavy metal poisoning risks. Republished by OSAC, U.S. Department of State. https://www.osac.gov/Country/Zambia/Content/Detail/Report/c2a686e3-348b-443a-aa4a-276f829af39e

9.       U.S. Embassy Lusaka (2025b). Health alert: Travel restrictions after toxic mine spill. 6 August 2025. Republished by OSAC, U.S. Department of State. https://www.osac.gov/Country/Zambia/Content/Detail/Report/22dfd3f7-30e3-4a45-a4d2-27e1866bfd8e

10.    World Health Organization (WHO) (2019). Exposure to cadmium: a major public health concern. WHO/CED/PHE/EPE/19.4.3. https://tdr.who.int/home/our-work/global-engagement/WHO-CED-PHE-EPE-19-4-3

11.    World Health Organization (WHO) (2022). Arsenic. Fact sheet, 7 December 2022. https://www.who.int/news-room/fact-sheets/detail/arsenic

12.    World Health Organization (WHO) (2026). Lead poisoning. Fact sheet, 10 June 2026. https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health