Tackling Water Hyacinth at Hartbeespoort Dam
The Hartbeespoort Dam in South Africa is facing a growing environmental challenge, with the invasive water hyacinth rapidly taking over the waters.
To fight this issue, the South African Department of Water and Sanitation, in collaboration with Rhodes University’s Centre for Biological Control (CBC), has come up with a unique solution: introducing Weevils to help control the spread of this harmful plant.
The Latest Approach: Weevil Release
On March 17, 2025, Water and Sanitation Deputy Minister Sello Seitlholo and Professor Julie Coetzee, the Deputy Director of CBC, took a significant step in the fight against water hyacinth.
They officially released the Salvinia weevil, an aquatic insect, into Hartbeespoort Dam.
This small creature is known for feeding on the invasive water hyacinth, making it a natural enemy to the plant.
The Salvinia weevil is a subaquatic herbivore that has been successfully used as a biological control agent in various parts of the world.
This approach is based on natural methods to curb the spread of invasive species, reducing the need for harmful chemicals or drastic interventions.
The Battle Against Invasive Hyacinth
Water hyacinth, a plant originally from South America, has been causing trouble at Hartbeespoort Dam since 2011.
Over the years, it has spread to various regions in North West and Gauteng provinces, even reaching the Limpopo River, which marks South Africa’s border with Botswana.
The hyacinth poses a significant threat to South Africa’s water resources, disrupting aquatic ecosystems and threatening local biodiversity.
In response, CBC has spent several years researching the Salvinia weevil, testing its effectiveness as a biological control agent.
By late 2024, the necessary approvals were granted to release the weevil into the dam, marking a critical moment in the ongoing efforts to manage the spread of this invasive plant.
What Is Water Hyacinth, and Why Is It a Problem?
Water hyacinth is a floating aquatic plant native to South America that has become an invasive species in many parts of the world.
Its rapid growth is a major concern, especially in places like Hartbeespoort Dam.
The main driver behind this growth is an overload of nutrients in the water, largely from untreated sewage from surrounding settlements, agricultural runoff, and fertilizers from nearby golf courses and gardens.
These nutrient-rich conditions create an ideal environment for the water hyacinth to thrive, outcompeting native plant species and choking waterways. Without intervention, it can significantly disrupt the ecosystem, affecting water quality and local wildlife.
Will the Weevils Be Effective?
The big question now is whether the introduction of the Salvinia weevil will be enough to curb the water hyacinth’s spread.
While the weevils have shown success in other parts of the world, it remains to be seen how they will fare in the unique conditions of Hartbeespoort Dam.
It’s a promising step, but only time will tell how well this biological control measure will work in the long term.
The fight against invasive species like water hyacinth is a complex challenge, and the use of natural predators like the Salvinia weevil represents an innovative and sustainable approach to managing the problem.
As the situation develops, it will be interesting to see how this solution evolves and whether it can help restore balance to Hartbeespoort Dam.