Climate change is likely to contribute to the deterioration of water quality in South Africa’s rivers and dams, which, says SRK Consulting partner and principal water and environmental scientist Manda Hinsch, may result in water authorities “raising the bar” for water discharged by industry and mines.

While both government and industry have aired concerns about climate change and its impact on water quantities, there has been “insufficient” attention paid to its effects on water quality.

Variable rainfall patterns caused by climate change have become evident in more frequent high-intensity downpours in parts of the country, Hinsch noted in a statement released on Wednesday.

“This means high-velocity runoff, accompanied by both increased leaching of soil nutrients  . . . fertiliser and wash off of urban pollutants – which end up in our water impoundments.”

She added that global research had confirmed that more intense precipitation and increased runoff meant more pollution entering waterways, with one of the more dramatic consequences being blooms of harmful algae and bacteria.

Continued nutrient enrichment of water gradually reduced its quality, resulting in significant implications for the environment, as well as downstream use, said Hinsch. In areas, where these heavy rainfall events are interspersed with hot, dry periods, high levels of evaporation could further increase the concentration of nutrients.

Additionally, she noted that water quality was also likely to be compromised in areas where climate change resulted in less rainfall.

Hinsch stressed that these negative impacts on water quality would exacerbate an “already problematic situation”, where the widespread malfunctioning of municipal wastewater treatment works was contributing to low-quality discharge into rivers and dams.

“In response to the declining quality of water, the relevant authorities may well have to take further policy and regulatory steps,” Hinsch stated, adding that mines and industry should not be “caught unaware” if water quality standards became more stringent.

Hinsch emphasised the integral connection between water quantity and quality when developing water management plans – be they for local government or private enterprises.

She added that, while these plans needed to be multifaceted and focused on local conditions, there was growing appreciation of the role of wetlands in water management.

“Wetlands play a vital role in controlling the flow of surface water and reducing runoff, while also trapping sediments and removing pollutants to help purify water,” she said.

Hinsch was hopeful that there would be greater use of attenuation ponds and constructed wetlands in future as part of a national response to climate change and more variable rainfall patterns, adding that the strategy could also be applied by mines and certain industries.