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Report on the scientific investigation of the impact of Marange diamond mining operations on water quality in the Save and Odzi rivers
Zimbabwe Association of Environmental Lawyers
July 30, 2012

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Executive Summary

The study of the impact of mining activities on the water quality of the Save and Odzi rivers was commissioned by the Zimbabwe Environmental Law Association (ZELA) in the period 5 - 13 July 2012. This followed widespread reports that water quality had deteriorated to the extent that most ecosystem services (potable water, livestock watering and irrigation) that used to be derived from these natural ecosystems had been lost. The objectives of this study were to determine the water quality in the Save and Odzi Rivers and make appropriate conclusions about the state of the environment and the potential impacts on human health and livelihoods in the Marange diamond mining region. Ten study sites were sampled and this included suitable reference sites were selected on each river outside the diamond mining areas to give comparison of the effects before and after mining discharges. Twenty physical and chemical water quality parameters were measured; along with nine heavy metal elements and four microbiological parameters. The results were evaluated against established W.H.O. standards and Zimbabwe Effluent Standards.

The results of this study have shown large-scale impacts that include siltation, chemical pollution and also heavy metal pollution. All these arise as by products of the mining processes. Turbidity and total solids exceeded the environmental limits. Water of high turbidity (hazey, murky water) cannot be used as potable water, and the high total solids also imply that it cannot be used as irrigation water as well as this will damage infrastructure. Downstream of mining activities the water has turned into a red ochre colour, thereby affecting the health of the river system. When in contact with the skin, the water and mud were itchy. It is most likely that the subsistence artisanal fishing that took place before is no longer possible at affected river sites, thereby impacting negatively on people's livelihoods. Similarly, pH was in the high alkaline range as well as C.O.D. These parameters were indicative of some chemical pollution in the rivers. The pH that is alkaline (hard water) is corrosive and can damage plumbing equipment and clothes. High levels of fluoride in the water pose the risk of diseases such as dental and skeletal flourosis. Dental flourosis relates to the poor development of teeth, while skeletal flourosis is a bone disease caused by excessive consumption of fluoride.

Levels of heavy metals showed high concentrations of iron, chromium and nickel in the water. These elements are the major constituents of ferro-silicon, a chemical compound used in the diamond extraction process. Chromium and nickel are potentially carcinogenic agents (cancer causing agents) and therefore they pose an immediate health risk to people and livestock. The high levels of iron in water suggest that the local populations could be at risk of iron poisoning, as they exceeded stipulated W.H.O. standards. Dangerous levels of bacterial contamination (high total and faecal coliform counts) mainly of faecal origin, were detected in the water. The exact sources could not be determined but the mines have to explain and show how their sewage is treated and disposed of in the mining area. This means sewage treatment facilities must be in place for evaluation. The presence of pathogenic bacteria such as Salmonella also represents an immediate health risk for the local communities. A water quality index (WQI) was calculated for each of the river sites, and results showed that most of the river sites were classified as BAD water quality and the reference sites as MEDIUM quality.

The results of this study clearly show the environmental and potential health risks to people and their livelihoods as a result of poor mining practices in the Marange diamond region. Access to this area is severely restricted, but the mines can only be exonerated if they allow independent studies to evaluate the environmental impacts arising from their mining activities. It is recommended that the necessary infrastructure to process ALL waste water from the mines should be put in place, and as part their community responsibility, the mines must facilitate the clean up process. The problems of water quality and environmental degradation need to be addressed in the Marange area before there is irreparable damage to the environment and people's livelihoods.

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