iSimangaliso’s bold management strategy is paying dividends. During a R65 million St Lucia Estuary restoration project, some 1.4 million cubic metres of dredge spoil have been removed and water levels in Lake St Lucia are at the highest level since 2002.
For 60-odd years, dredge spoil was artificially deposited in the natural course of the uMfolozi River by then conservation managers as it was thought that silt exacerbated from the canalisation of the uMfolozi River was the biggest man-induced risk to the 350km2 estuarine system.
In 2010, a multi-disciplinary research team drawing on independent peer-reviewed research was pulled together by iSimangaliso to concretise solutions towards resolving the acute hydrological problems facing the Lake St Lucia system. While silt is an issue, the science identified that the critical issue is fresh water and the uMfolozi River’s ability to act as the powerhouse that drives the natural process of the mouth. With support from the Global Environmental Facility and World Bank, iSimangaliso initiated this R63 million Lake St Lucia restoration project. (Note: A further R2 Million was subsequently added to the budget for work now in progress)
The health of iSimangaliso’s Lake St Lucia ecosystem is critical for some 80 000 people who use it extensively as part of their livelihood strategies. Tourism related directly to the Lake employs an estimated 8000 people locally. Income from iSimangaliso’s 510 000 visitors, 42% of whom are international, contributes some 7% to KZN Tourism GDP. The contribution to fisheries of the Lake St Lucia system is also significant locally, nationally and for Mozambique. It is expected that over time with good river flows, the rest of the obstacle between the uMfolozi and Lake St Lucia Estuary will erode and wash out to sea, as it would have during floods. The removal of thorn trees off the remainder of the dredger-created ‘island’ is being done to assist this. “The scene is now set for Mother Nature to continue the rehabilitation process. Good rainfall will be a key driver,” says iSimangaliso’s Senior Manager Research and Planning, Bronwyn James.
According to Professor Derek Stretch of the Civil Engineering Department at the University of KZN, the mouth restoration work “is very significant and will enable us to reverse some of the negative impacts of decades of dumping dredge spoil in that area and facilitate the more natural functioning of Lake St Lucia Estuary. At the moment, with a closed mouth from the drought and as the first part of the restoration work is underway, we are very likely in a sediment accumulation phase. This is however only the short term view, because once we enter a period with more rainfall, floods and tidal flushing associated with an open mouth this will result in a net loss of silt from the estuary.”