Explainer: Ridding the Vaal River of water lettuce

The move forms part of efforts to slow down the spread of the highly invasive and free-floating water lettuce.

Water lettuce is a poisonous and highly invasive free-floating freshwater weed that is normally found in lakes, dams, ponds, irrigation channels and slow-moving waterways in tropical, sub-tropical and warmer regions.

In January last year, Rudy Joles, CEO of Harties Foundation, spoke to Breakfast with Martin Bester to discuss the growing hyacinth problem at Hartbeespoort Dam.

It came amid growing concerns over the excessive growth of algae and water hyacinth.

Joles said almost 900 hectares of the Hartbeespoort Dam had been covered with hyacinth.

According to Joles, this is a problem that has been ongoing for more than 50 years.

In December 2023, the Vaal River saw an increase of water lettuce taking over the river, causing major concern among residents and authorities.

Rand Water believes the weevils and hoppers will assist in eating the water lettuce in the Vaal River.

"In addition, there will be a modest application of approved and permitted herbicides that will be released into the water under the guidance of senior and qualified Rand Water officials. The introduction of chemical control is a short-term intervention and will be followed by non-chemical medium and long-term interventions,” said Rand Waters' Leslie Hoy.

More weevils and hoppers will be released into the river before the end of summer.

Hoy said the water lettuce has had a negative impact on recreational activities, fishing and the environment as a whole.

Hoy added that there are a number of long-term solutions that can be put in place to get rid of the water lettuce in the river.

The length of the water lettuce changes daily, covering over 170 hectares of the water surface.

Hoy said the insects would not pose any danger to the water quality.