Invasive clearing in Cape Town: Black River

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Lying at the intersection of the N2 and N1 highways, the Black River, with its dense aquatic weed invasion, is a high-profile site.

Water hyacinth doubles its growth every 10 days at the height of summer and an integrated approach has therefore been adopted, using a combination of herbicide spraying, manual removal and mechanical removal (using large machinery) in the river.

The Black River is an inter-departmental project and the Invasive Species Unit (ISU) works closely with the Transport, Roads and Stormwater Department, as well as with friends stakeholder groups who focus on tributaries to the Black River.

To manage the invasion, the Black River has been divided up into five management sections. Booms made from recycled vegetable bag cloth and empty two litre plastic bottles have been placed across the river to cordon off the water hyacinth into different sections. The booms prevent the wind from blowing the water hyacinth along the river and make it easier for the teams to remove the water hyacinth manually, section by section.