Between risk and resource – Mine-Influenced Water (MIW) as challenge and opportunity

Mining, particularly gold extraction, represents a significant economic sector but also causes substantial environmental impacts through mine-influenced water (MIW). This contaminated water, especially acid mine drainage (AMD), poses a serious threat to the quality of surface and groundwater and adversely affects both human health and ecosystems. In countries such as South Africa, which are heavily reliant on mining and simultaneously face water scarcity, MIW presents a complex and pressing challenge. The research project MAMDIWAS (Mine Water as a Driver for Change to Enhance Water Security in South Africa), adopts an integrative, technology-based approach to the sustainable utilization of MIW. The project aims to reconceptualize MIW as a resource that can be harnessed for drinking water supply, agriculture, and raw material recovery. At this stage it focuses on integrated water resources management, i.e. (i) assessing water quality within the catchment area of mines, (ii) identifying key pollutants originating from MIW and evaluating their toxicological effects, and (iii) exploring reuse options and analyzing public acceptance, with the goal of deriving informed strategies for water protection and resources management.

Two sampling campaigns were conducted in 2024 and 2025 along two rivers downstream of gold mines west of Johannesburg, as well as on the premises of an active gold mine. The collected samples were analyzed in the laboratory for heavy metals (including Al, Sr, Fe, Mn, Pb, Cd, Co, Cr, Cu, Ni, Zn, Mo, V, Si, Ar, U) and other relevant parameters. The campaigns were carried out under both normal and low-flow conditions. In addition, in-vitro toxicity tests were performed to assess mutagenic and genotoxic effects. The overarching objective is to evaluate ecological and health risks associated with MIW, particularly in regions where such water is used for drinking or irrigation, thereby laying the foundation for sustainable water management. First results indicate that local conditions influence the occurrence and toxicity of MIW pollutants, e.g. geological settings and climate seasonality. Furthermore, samples taking downstream from mining sites show that MIW pollution concentrations are declining due to dilution, sorption, and degradation. However, at the same time toxicity analyses feature an increase further downstream. A working hypothesis that additional pollutants from formal and informal settlements of mostly mine workers influenced this increase was confirmed by additional analysis of organic pollutants. As a next step water re-use options for these different MIW qualities will be derived.