Cape Town - Residents, conservation groups and City staff gathered on Freedom Day for the 26th annual drawdown of the Zeekoevlei weir at the False Bay Nature Reserve, the City’s first Ramsar designated Wetland of International Importance, which recently paved the way for getting Cape Town declared a Ramsar City.
A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention.
During the drawdown, the False Bay Nature Reserve staff lowered the weir’s six sluice gates to flush the vlei of all the pollutants that had built up in the system over the past 12 months, and enable necessary clean-up work to be undertaken in Zeekoevlei, once regarded as one of the most polluted water bodies in the country.
The Friends of Zeekoevlei and Rondevlei (FOZR), a key community conservation group that will be assisting the City in the clean-up work, said that the drawdown was an important intervention, first introduced in 1997.
Deputy mayor and spatial planning and environment Mayco member Eddie Andrews said: “We usually open the sluice gates annually, on April 27, which also happens to be Freedom Day. This is after the first rains, at the end of autumn. The lower water levels will make it easier for our crews to do manual clean-up with the removal of litter and water hyacinth.”
This work will get started within the next two weeks, once enough water has drained from the vlei. Andrews said the sluice gates usually remained open until mid-July, after several cold fronts have moved through Cape Town and flushed the system.
FOZR vice-chairperson Tom Schwerdtfeger said: “This window of opportunity also allows for the removal of reeds and alien vegetation.
Schwerdtfeger said that they had assisted in removing invasive water hyacinth, the world’s most invasive and harmful aquatic weed, in Zeekoevlei over the last six weeks.
Alex Lansdowne, the deputy chairperson of the mayoral advisory committee on water quality in wetlands and waterways, explained that the annual Zeekoevlei drawdown mimics the natural flushing process that would have occurred in Cape Town lowland waterbodies hundreds of years ago.
Lansdowne said the draw down flushes the vlei, which will refill with fresh ground water during the rainy season, and a new weir and fish ladder will be built for Zeekoevlei as part of the inland water quality improvement programme.
“This will allow for better mimicking of natural hydrological processes. The fish ladder is an important innovation and will allow for the restoration of fish species which historically would have migrated from the ocean into the vlei,” Lansdowne said.
The spatial planning and environment directorate has budgeted R49 million over the next three financial years for the lowering of the Zeekoevlei weir. According to FOZR chairperson Sidney Jacobs, they had planned all the activities that would happen after the draw down with military precision.
He added that the mouth of the Big Lotus River will be scraped by contractors using excavators so that all embedded litter can be removed to the correct dumpsites by dump trucks, and FoZR will play a supporting role to the nature reserve in removing overgrown reeds that had taken over areas in front of homes.
kristin.engel@inl.co.za