BACK TO BASICS WITH WATER QUALITY MONITORING

discharged. This also provides a challenge to the dischargers, who need to be able to isolate their own impact on the resource, especially if there is more than one discharger at the same stretch – but on opposite sides – of the river. The readily available data on the number of monitoring points reflects the period between 1971 to 2011; later data is not so easily accessible.

The growth of industries and population is placing a greater strain on the country’s water resources. Discharges into rivers and dams must be more closely tracked so that authorities can identify the source of pollution without delay,

Manda Hinsch, partner and principal scientist at SRK Consulting

and respond with the necessary action,” says Manda Hinsch, partner and principal scientist at SRK Consulting.

Currently, resource monitoring points are often so far away from discharge points that the authorities can only scrutinise the quality of water being

Dylan Harrison, data scientist at SRK Consulting

“The statistics on the number of monitoring points that are reported in the public domain seem to suggest a decrease over recent decades,” adds Hinsch. According to publicly available figures, the number of monitoring points from all stations at dams and lakes countrywide peaked at 243 in 1987. By the time the National Water Act was passed in 1998, this number had dropped to 216. By 2011, it was just 133.

A similar trend appears to apply to the number of monitoring points in the country’s rivers, she explains, although the number climbed steadily until 1998 to 872. In little over 12 years from that date, this number had halved to 441.

“The lack of water quality data also makes it difficult for industry to check that their water management is effective,” she explains. “In a recent project, for instance, we were investigating the possible ingress of river water into an aquifer directly adjacent to the Vaal River – but there is not enough information available on the recent water quality of the river to investigate without doing isotope tests.”

Sampling points

It is important that the sampling points are close enough up- and downstream of discharge zones for scientists to draw conclusions about where any identified contamination has originated. In the case of large water users like mines, who operate in compliance with a water use licence (WUL), they are required to monitor the nearby rivers to pick up possible impacts from diffuse sources.

“In urban areas, small industrial businesses sometimes discharge into sewers; it is assumed that the water services authorities receive their effluent where the wastewater treatment works may not necessarily be equipped to treat that type of effluent,” she maintains. “There should be sufficient sampling points for stakeholders to accurately confirm that their discharges are not adversely affecting water quality in rivers.”

Dylan Harrison, data scientist at SRK Consulting, notes that the monitoring of water quality produces reams of data that can provide a range of valuable insights. “With the analytical information technology available to us, and the skills of data scientists, there is so much more that can be derived from data to assist with decision-making.”

Another crucial reason for reliable and current water quality data relates to the directions contained in WULs, as the requirements of each licence are matched with the quality of water that the user must maintain.

“What is critically important about consistent and comparable water monitoring is that it generates a trend,” he says. “This allows scientists, engineers, clients, regulators, and other stakeholders to understand changes in water quality over time – to inform the necessary responses.”

Hinsch points out that single or sporadic samples have limited usefulness, as these could reflect just the result of an infrequent discharge or may be inaccurate for some other reason. Regular samples from the same point allow for the accuracy of readings to be confirmed and highlight changes in quality that require investigation.

To give value and purpose to the monitoring activity, it is also vital that the sampling results and analysis find their way into a responsive water management strategy. As important as monitoring is, it is really only the beginning of a broader and more demanding process.

“The reason for the monitoring is so that experts can analyse the results of the sampling and take necessary action if water quality is found to be falling short of regulated standards,” Hinsch says. “The monitoring is only useful if it leads to a programme or strategy that improves water quality.”