Long-term assessment of the surface water quality in the Blesbokspruit Ramsar Wetland

M.Sc. (Environmental Management)Surface water quality in the Blesbokspruit Ramsar wetland has been an area of concern since the 1990s, especially following the authorised and subsidised pumping of underground waters—high in salts—from Grootvlei Mine Shaft No. 3. The pumping was necessary to maintain their underground mining operations and to avert flooding of low-lying areas from decantation of derelict gold mines in the Blesbokspruit catchment. High levels of salt, coupled with a change in the flow of the system, contributed to the loss in the ecological character of the Blesbokspruit wetland in 1996 and, its subsequent listing on the Montreux Record during the same year. In Ramsar terms, the Blesbokspruit was under threat and on the brink of losing its international Ramsar status if management action was not taken to improve the surface water quality of this wetland. The Blesbokspruit has become, since 1996, a wetland in need of restoration to optimum hydrological conditions, i.e. water quality and quantity. A return to desirable water conditions in the Blesbokspruit wetland would enhance aquatic species diversity and abundance—especially the important waterfowl species that gave the Blesbokspruit wetland its international reputation. With the shutting down of the mine and the cessation of pumping operations at Grootvlei (Aurora) Mine in December 2010, the surface water in the Blesbokspruit wetland should have improved and enhanced the agricultural activities (irrigation and livestock watering) adjacent to this wetland, as well as contributed to healthier aquatic conditions much needed by local and migratory birds. An investigation of the surface water quality in the Blesbokspruit wetland was performed on historical water quality data for the period 2000 - 2011, obtained from Rand Water. The study revealed that there was a distinct seasonal and spatial pattern in the salts (i.e. sulphate, chloride, sodium, and magnesium), and related electrical conductivity and pH values for sites downstream of the underground water pumping point at Grootvlei Mine Shaft No. 3. Such observable seasonal and spatial patterns in the sites downstream of the underground mine-water discharge point could validate previous findings that had associated saline pollution with the pumping operations of Grootvlei Mine. Inter-annual trends showed a progressive decline in the concentrations of the salts and associated electrical conductivity values, with pH readings between neutral and slightly alkaline. Improvements in the salinity and acidity levels in the Blesbokspruit wetland could then be associated with the number of water management interventions adopted, particularly by Grootvlei Mine, from the mid-1990s until December 2010 (the year when mining and pumping operations ceased at Grootvlei Mine). Nevertheless, during the year 2011, the chemical properties of the Blesbokspruit revealed a step alteration—a substantial drop in concentrations of sulphate and magnesium salts—following cessation of underground pumping the preceding year, also confirming previous investigations linking saline water contamination to underground mine-water pumping operations at Grootvlei Mine