Dam in Delta Park Cleared of Water Hyacinth
February 24, 2024
What was the problem?
The Florence Bloom Dam in Johannesburg’s Delta Park was almost entirely smothered by water hyacinth, an alien invasive plant that blocks off sunlight, kills aquatic ecosystems, and severely degrades water quality. Rapid-growing and notoriously hard to eradicate, the hyacinth problem was worsened by a six-week sewage leak into the dam, which made the water unsafe for volunteers and further fueled the weed’s explosive growth.
How did they solve it?
The Delta Park Users Group, led by Shirley Tebbutt, worked hard, trying a combination of different methods to remove the hyacinth in a lasting and thorough way.
What made it work?
Biological control: Experts from the South African Institute for Aquatic Biodiversity (SAIAB) and the Centre for Biological Control (CBC) stepped in to help. About 25,000 hyacinth hopper insects were put into the dam. These insects ate the plant's sap, causing diseases that slowly killed the hyacinth, especially in the spring when plants grow back. The hoppers do not eradicate the invasive weed but reduce its population to a level where it can be controlled.
Manually removing the plants: At first, volunteers used canoes to float around the dam and pull plants out. To speed things up, the group also hired a tractor loader backhoe (TLB) to haul out many of the plants. “The TLB was expensive, but each bucket load was equal to a loaded canoe, and it was fun watching the rapid progress,” Tebbutt told The Randburg Sun. The group relied on community donations to hire the TLB.
Meticulous follow-up: Following cleaning most of the water hyacinth, it was necessary for two people to painstakingly scour the dam with a canoe and pull up every single plant that remained, especially those hiding in the reeds. Because hyacinths spread so rapidly, a single plant left can grow to cover the dam.
Stop the spread: It is critical to know that water hyacinth must not be moved from one water source to another. It is illegal to plant or move hyacinth according to the Biodiversity Act. Tebbutt says that if you notice water hyacinth in a water body in your community, you must report to the CBC – cbcinfo@ru.ac.za or the South African National Biodiversity Institute (SANBI) – invasivespecies@sanbi.org.za
Stopping sewage spills: Sewage spills leave nutrients that weeds thrive on. Reporting and working with local wastewater treatment plants to prevent sewage from entering dams and rivers is vital for both stopping hyacinth and promoting public health.
For more information or to get involved, contact the Delta Park Users Group through Shirley Tebbutt at etebbutt@worldonline.co.za or 082 596 7500.
Join the fight against invasive species
Is your local water body facing a similar issue? Discover how to set up a biological control program and involve your community. Visit the link below for more details.
Acknowledgements:
Original article written by: Mthulisi Lwazi Khuboni
Photograph supplied by: Mthulisi Lwazi Khuboni
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