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

No information is available on the present situation, though it is well known that large numbers of alluvial miners
panned for gold near the town of Pilgrims Rest during the late 19 th and early 20 th Century. It can be anticipated
that a few small-scale miners will still undertake occasional exploratory work in the upper reaches of this subcatchment.
5.6.4 Monitoring systems
The Department of Water Affairs and Forestry (DWAF) routinely collects water samples and gauges flows in this
sub-catchment, as part of its national monitoring programme. In addition, DWAF also regulate all large (> 150
m 3 /day) water abstractions, and monitor the quantity and quality of all effluent discharges through a system of
effluent discharge permits or licences. Each licensed effluent discharger is required to carry out a routine
monitoring programme of the flow and quality of their effluent and supply this to DWAF. The Department then
conducts a randomised series of audit samples to check the veracity of the effluent returns submitted by each
discharger.
5.6.5 Water quality data
A few water quality data for four sites along the upper reaches of the Blyde and Ohrigstad rivers were available
from the Department of water Affairs and Forestry. These data are presented in Table 5.12, below.
Table 5.12: Water quality data for four sites on the Blyde sub-catchment. All values are given in mg/litre,
except pH (log units).
Sampling Site
Parameter Blyde River at Blyde River at Blydepoort Ohrigstad
Willemsoord Chester
Dam
Dam
TDS 140 140 140 46
pH 7.55 7.35 8.30 6.65
Ca 30 28 32 31
Mg 8 11 11 10.8
Cl 5.4 5.3 4.6 7.2
SO4 7 6 9 5
Total Alkalinity 64 67 70 56
NH4-N 0.08 0.07 0.2 0.13
NO3-N 0.23 0.29 0.35 0.15
PO4-P 0.010 0.009 0.009 0.007
These data reflect the influence of the dolomitic formations on the water chemistry and also the presence of
agricultural return flows enriched with fertilizers.
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