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

Water quality data for three sites along the Sand River (middle, lower-middle and lower reaches of the subcatchment)
were obtained from the Department of water Affairs and Forestry. These data are presented in
Table 4.23, below.
Table 4.23: Water quality data (median and 95 th percentile values) for three sites along the Sand River. All
values are in mg/litre except and electrical conductivity (milliSiemens/metre), and pH.
River Reach
Parameter
Middle Lower-Middle Lower
pH 7.67 - 8.48 7.05 - 8.03 7.65 - 8.30
Electrical Conductivity 59.1 - 115.2 9.5 - 39.1 59.0 - 79.3
Ca 28.2 - 62 6.2 - 22 31.2 - 41.8
Mg 21.2 - 54 3.4 - 12.9 20.2 - 27.2
Na 46.5 - 125.3 5.3 - 32.8 55.1 - 81.4
K 4.2 - 7.1 0.9 - 4.2 4.5 - 5.5
Total alkalinity (CaCO3) 172 - 345 26.7 - 117.2 159.9 - 192.4
Cl 54.6 - 178.1 10.3 - 33.9 66.5 - 112.7
F 0.23 - 0.43 0.08 - 0.26 0.27 - 0.43
Si 9.4 - 13.3 7.7 - 9.9 9.73 - 12.08
SO4 12.5 - 40.9 3.6 - 10.7 14.7 - 34.3
NH4-N 0.06 - 0.21 0.05 - 0.12 0.05 - 0.21
NO3-N 0.02 - 0.45 0.06 - 0.35 0.02 - 0.35
PO4-P 0.03 - 0.11 0.01 - 0.05 0.03 - 0.08
These data (Table 4.23) show that the Sand River water is moderately mineralised and is subject to enrichment
by plant nutrients (nitrogen and phosphorus), probably as a result of agricultural return flows and discharges of
treated sewage effluent. The concentration ranges of the normal water quality parameters indicate that the
water is generally of a good quality and fit for most uses except irrigation on sensitive soils.
4.20.6 Implications for water quality and quantity management
The available evidence suggests that the very limited mining activities in this sub-catchment are unlikely to have
any significant impact on either the local water resources or on water quality in the area. Most impacts would be
likely to consist of a minor increase in suspended solids concentrations during periods of high flow following
rainfalls. The possible exceptions to this statement would be a possibility of minor acid mine drainage from the
abandoned pits and adits of the Messina Copper Mine and the presence of small quantities of arsenic
associated with alluvial gold diggings. If these alluvial miners use mercury to separate out the gold, then there
is also a risk of mercury contamination.
The Soutpansberg Salt Works extract salt from evaporite deposits located to the south of the town of Louis
Trichardt. There is a minor risk of localized ground water contamination in this area.
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