OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

agriculture consume most of the water used in the upper and central reaches of the sub-catchment. Formal
irrigation boards control the allocation of water to each of the irrigation schemes in the sub-catchment.
Contamination of local water resources by faecal coliform bacteria is a consequence of inadequate sanitation
and the simultaneous use of water resources for domestic supplies and stock watering. Most of the mines and
industries in the sub-catchment rely on water supplies from local boreholes.
5.4.1.5 Water management systems
The South African Department of Water Affairs and Forestry (DWAF) is responsible for the management of all
aspects of water supply and water use in the sub-catchment. The Department operates a system of routine flow
gauging at the Arabie Dam and other water supply dams, and pays particular attention to monitoring the
quantity of water supplied to irrigation schemes and towns, as well as increasing attention to the quality of
agricultural return flows and effluent discharges to the Olifants River. The various irrigation boards are
responsible for the day-to-day management of water allocations for irrigation.
5.4.1.6 Human impacts on water resources (excluding mining)
The following activities can be expected to have an impact on water resources in the Middle Olifants subcatchment:
• Landfills and solid waste disposal sites at all towns and larger settlements;
• Disposal of liquid (domestic, light and heavy industrial) effluent at all towns;
• Moderate volumes of runoff from towns, as well as all other urbanized areas;
• Non-point domestic effluent from numerous small settlements and farms;
• Minor non-point impact from non-intensive commercial or subsistence agriculture;
• Non-point impact of agricultural return flows from intensive irrigation areas; and
• Litter and domestic garbage discarded alongside the many roads that traverse the sub-catchment.
Examples of the types of effluents that are discharged into this sub-catchment are shown in Table 5.7, which list
the water quality characteristics of four sewage treatment plant effluents.
Table 5.7: Water quality data for three sites on the Olifants River in the Middle Olifants sub-catchment. [All
data are given in mg/litre, except pH (log units) and electrical conductivity (mS/metre)].
Parameter Loskop Outflow Olifantspoort Rooipoort
pH 7.3 8.0 8.0
Conductivity 150 140 120
TDS 1105 900 800
Ca 75 60 45
Mg 60 55 50
Na 240 200 160
ccciv