For many years the debate on the quality of the water on the West Rand has been raging. Now the Cradle of Humankind World Heritage Site Management Authority (COH WHS MA) has released its monitoring report on water in the area and the results will go a long way to informing the discussion on the issue.

Dawn Robertson, CEO of the Cradle of Humankind World Heritage Site, says: “Previously there was a very poor understanding of both the surface and ground water in the area and so the COH WHS MA commissioned a situation assessment into the water quantity and quality which will be used by the Department of Water Affairs in charting a way forward on the matter.”

The COH WHS Management Authority recognised its mandate to protect and preserve the heritage site and so this study was conducted to determine the impact that human activity has on the water resources of the area.

One of the major concerns with that has been raised with regards to water in the world heritage site is AMD. AMD occurs when acid, metals and sulphates are released into the water system as a result of disused mine shafts filling with water and overflowing (or decanting) onto the surface.  However, the impacts of AMD are as important as the impacts of agricultural activities in the area.

Robertson says: “This is a particular concern in the COH WHS as it is downstream of various disused mines on the Western Basin and in recent years this has negatively impacted on aquatic life and the quality of water in the area.”

The results from the study are both interesting and surprising.

The first finding was that AMD is not the only factor that is degrading the water quality in the area. The other factors include the discharge of treated municipal wastewater effluent into the river system, impacts from agricultural activities, high load-bearing on-site sanitation facilities in the areas not served by a municipal sewerage system, and sanitation and waste concerns associated with informal settlements.

Pete Mills, Director: Environment and Conservation for the COH WHS Management Authority, says: “With all these water issues it was essential to understand how these factors impact on the thirteen listed fossil sites in the COH WHS. As a result a hydrovulnerability assessment was done and through this study it was established that the risks to most of the fossil sites are minimal.”

Nine of the fossil sites reflect a very low or low vulnerability due to their location. This low vulnerability was assigned because (a) they are situated in groundwater compartments that are hydrogeologically separated from those where the contaminated water is found and (b) are at an elevation above the ambient groundwater level.

Bolt’s Farm reflects a very high vulnerability. Sterkfontein Caves was assigned a high vulnerability despite the fact that the site has to date reflected a very low historical impact in terms of water quality. This is a precautionary measure because the caves intersect the water table.

The Swartkrans, Minnaars and Plover’s Lake sites reflect a moderate vulnerability. From this assessment it can be concluded that the majority (70%) of the fossil sites in the COH WHS are not under threat from either changes in surface or ground water quality or quantity. More importantly, however, the authorities now know where to concentrate their efforts to protect those sites that are more vulnerable.

A petrographic study and laboratory kinetic leach tests were conducted to study the impact of AMD on dolomite. The study found that the dolomite initially acts as a buffer and helps to neutralise the water entering the natural groundwater system due to dissolution of the dolomite. However, this effect reduces over time, diminishing both the neutralising influence and the dissolution of the dolomite.

As a result of the hydrovulnerability assessment and dolomite leaching studies, it was decided to earmark the more vulnerable fossil sites for short-, medium- and long-term monitoring. This will allow the COH WHS MA to continue to observe and assess any changes in the situation specific to these sites.

Now that the assessment has been completed and the report sent to the Department of Environmental Affairs, the Department of Water Affairs, it will help to inform the Government’s approach to the issue.

Mills explains: “This report has provided the means to objectively gauge the impact of varied and numerous threats to and on the water resources, and to develop a coordinated, appropriate and cost-effective water resources monitoring programme.”

The Department of Water Affairs (DWA) is in the process of implementing a mine water control, management and treatment system in the Western Basin, while the COH WHS MA is currently rolling out a water resources monitoring programme in conjunction with the DWA. This monitoring will continue to track changes to the water resources system over time and to inform the relevant authorities accordingly.

In addition to collaborating with government departments and institutions the COH WHS MA also partners and collaborates with other organisations to keep track of the challenges posed by AMD. The COH WHS MA is a member of the Western Basin Void Monitoring Committee convened by DWA as well as the Inter-Governmental Task Team on AMD.

Mills says: “The Department of Water Affairs (DWA) continues to support the Management Authority in its water-resources monitoring activities in the area by providing monitoring boreholes and instruments and the AMD concern is being addressed by the Inter-Governmental Task Team (IGTT) on AMD.”

The IGTT, in accordance with the recommendations of the team of experts report to the Inter-Ministerial Committee (IMC) on AMD, has implemented measures to control the decant of AMD from the Western Basin. This will roll out in the very near-term.

Robertson concludes: “The COH WHS is one of the richest fossil sites in the world and we are committed to protecting and preserving this significant heritage site also in regard to its water resources within the Karst environment. We will continue to work with all the government departments to find a sustainable solution to this environmental challenge.”

MEDIA RELEASE issued by Jade Archer – jadea [at] kagisotv.co.za

DOWNLOAD a Facts Sheet on the findings of this project (pdf 85 kb): cradle-of-humankind-water-monitoring-fact-sheet.pdf