Hartbeespoort hyacinth cover drops below 10%

By Lebone Rodah Mosima 

Water hyacinth coverage on Hartbeespoort Dam has been contained to 9.77% of the reservoir’s surface area, despite heavy rains and nutrient-rich inflows that accelerated growth this season.

Magalies Water and the Department of Water and Sanitation (DWS) said on Thursday that this was significant progress in a nearly three-year effort to restore one of South Africa’s most troubled dams.

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Recurring algal blooms, sewage-fed nutrient loading and invasive water plants have long undermined water quality, recreation and ecosystem health in the popular dam.

Magalies Water was appointed by DWS in April 2023 as the implementing agent for water resource planning and management in the upper Crocodile West River Catchment and Hartbeespoort Dam.

Its turnaround strategy centred on 10 objectives: managing alien invasive species, tracking pollution, improving water quality monitoring, remediating hyacinth and algae, revamping inlet controls, engaging stakeholders, supporting research and innovation, curbing nutrient loading at source and implementing an integrated water resource management plan.

The control of the invasive water hyacinth has been a primary focus, and has been tackled through “manual, mechanical and biological control”.

Contractor Hyamatla Organics was appointed to remove floating plants and debris from the dam and its shoreline. Rhodes University biological control specialists were brought in to deploy control agents, including Megamelus scutellaris, a sap-feeding insect used to suppress the hyacinth.

Physical removal efforts were stepped up during the peak regrowth period between September and January, when germination and spread usually accelerate.

“To address this, a ramp-up strategy was implemented to boost the removal rate, along with additional booms and noodles aimed at trapping and maximizing removal at specific locations,” Magalies Water said.

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Although heavy rains disrupted