01 Aug 2025

Invasive water hyacinth threatens South Africa’s dams

Water hyacinth, an invasive alien species originally from South America, has become one of the most aggressive aquatic weeds in the world. In South Africa, this floating plant is rapidly spreading across freshwater bodies, choking waterways, depleting oxygen and disrupting aquatic ecosystems. Record rainfall and rising nutrient loads in the Vaalkop Dam in the North West province have caused the coverage of hyacinth on the dam’s surface to grow tenfold (from 100 hectares to over 1,000) between January and May 2025 alone. This has reduced water quality, harmed biodiversity and brought recreational use of the dam to a near standstill. Similar challenges have been reported at Hartbeespoort, Roodeplaat, and other dams across the country.

Action and impact

Across South Africa, government, academia, private sector and civil society have begun to scale efforts to address the issue. The Department of Forestry, Fisheries and the Environment has partnered with organisations like the Centre for Biological Control (CBC) at Rhodes University to promote long-term, sustainable solutions such as biological control. At Roodeplaat Dam, the CBC has deployed Megamelus scutellaris, a small insect that feeds exclusively on water hyacinth, with early signs of success.

Tourism operators have joined the response in the North West, a similar approach is underway at Vaalkop Dam. This includes Finfoot Lake Reserve, situated adjacent to the dam, which is part of the Vaalkop Dam Alien Vegetation Action Group (VDVAG) along with neighbouring estates, having built three rearing tunnels for the insects with support from the CBC. “This is an ecological and water security issue that of course also has a negative operational impact for tourism operations that rely on dam waterway activity and conservation,” says Brent Dickson, Director at Dream Hotels & Resorts, which owns Finfoot. “We’re investing in solutions because if the ecosystem fails, everything else follows.”

Tourism as part of the solution

Dream Hotels & Resorts has contributed R20,000 through its NPO, Touching Dreams, toward expanding the biological control infrastructure. The group is facilitating roundtable discussions with the Department of Water and Sanitation, Magalies Water, Rustenburg Municipality and others to push for coordinated action. “Mechanical removal can clear the surface, but without addressing nutrient loads and enabling long-term biological control, the hyacinth will continuously return,” says Dickson. “We’re committed to working with environmental experts and authorities to build the kind of multi-layered response this crisis demands.”

Finfoot will soon launch a birding challenge with sister properties Nibela Lake Lodge and Little Switzerland Resort to encourage ecotourism while supporting ongoing environmental work.

With the growing scale and speed of the infestation and its knock-on effects, there is recognition that isolated efforts are not enough. Rather, coordinated, science-backed responses supported by cross-sector collaboration remains the most viable path forward, not just for the health of South Africa’s dams but for the people, businesses and ecosystems that rely on them.