As the invasive water lettuce continues to multiply along the Vaal River, Rand Water has begun an integrated response to halt the growth, spraying herbicide on the plants and releasing weevils as biological control agents. While the response is seen by some as necessary to urgently address socioeconomic implications, it's seen as controversial by others.

'Under ideal conditions, it is safer and smarter to just implement biological control," said Dr Leslie Hoy, the environmental management services manager for Rand Water.

"But you have a huge mat [of water lettuce], and that mat is impacting on people's livelihoods, impacting on tourism, and impacting on people who rely on fishing on the Vaal Barrage. So you need to deal with it."

Hoy was speaking to Daily Maverick on the banks of the Vaal River in Vanderbijlpark on Thursday, 15 February. It has become overrun with water lettuce and some water hyacinth - invasive aquatic species that have environmental and socioeconomic implications.

Water lettuce exploded along the Vaal River in December 2023, causing residents to urgently find a solution to deal with the ever-growing plants.

Rand Water was given an urgent general authorisation by the Department of Water and Sanitation (DWS) to begin an integrated approach to manage the water lettuce, which includes physical removal, biocontrol and chemical application, as advised by experts by the Department of Forestry, Fisheries and Environment (DFFE).

Glyphosate-containing herbicide was sprayed on the invasive water lettuce in sections of the Vaal River on 13 February in a sub-lethal dose. Rand Water said specific...