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

4.17.4 Monitoring systems
The Department of Water Affairs and Forestry (DWAF) do not carry out any monitoring of river flows or water
quality in this sub-catchment because of the scarcity of surface water. However, the department does
occasionally monitor the quality of water in local boreholes as part of its national ground water monitoring
system.
4.17.5 Water quality data
No water quality data were available for this sub-catchment. In view of the very limited mining activity, this
deficiency is not considered to be important.
4.17.6 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
had any significant impact on either the local water resources or on water quality in the area. Any impact would
be likely to consist of a minor increase in suspended solids concentrations during periods of high flow.
4.18 The Mogalakwena sub-catchment
4.18.1 General description
4.18.1.1 Hydrology
This sub-catchment consists of the area drained by the Mogalakwena River and its tributary streams, notably
the Nyl River in the upper reaches. This river system flows northwards from the area around the town of
Nylstroom and joins the Limpopo River downstream of the Laphalala River (Figure 4.2). The flow pattern in
this river is variable as a result of the prevailing low and unpredictable rainfalls (average 540 mm) though the
river is normally perennial and only dries up during severe droughts. Summer rainfalls cause a dramatic
increase in the flows of this river, though most of the tributary streams are highly seasonal and tend to flow
only during the summer months. The Nylsvley wetland is an extremely important wetland in the upper reaches
of the catchment and attenuates the flows contributed by the Nyl River to the Mogalakwena River.
The Mogalakwena sub-catchment contains several hundred small farm dams that are used to supply water for
domestic and irrigation purposes, as well as livestock watering (Boroto & Görgens, 1999). These farm dams are
responsible for most of the reduced flows that now characterize the Mogalakwena River.
Additional water supplies are piped into the catchment by the Magalies Water Board to meet the growing
demand for potable and industrial water in this sub-catchment.
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