iSimangaliso Wetland Park management has chosen a passive approach to managing the estuary mouth. It may need to rethink this approach with some urgency as circumstances have varied materially since the management strategy was devised.
Management of the iSimangaliso Wetland Park is a complicated business. The Park, which encompasses Lake St Lucia on the Zululand coast, is part of the largest estuarine lake system in Africa and is justly famous for its diverse wildlife and recreational activity. The unique beauty and diversity of the site was recognised in 1999 when it was proclaimed a World Heritage Site.
Lake St Lucia is an estuary, which means that it is sometimes open to the sea and sometimes cut off from it by a sand dune. The revised management strategy reconnects the uMfolozi River to the St Lucia estuary. It is intended to ensure that the combined system is able to better function as an estuary by being able to open itself to the sea more often than not. Now that the Umfolozi River has been mechanically re-connected to the St Lucia system, the dune was widely expected to breach naturally during the wet season of 2019/20, but this has not happened. The result is that silt from the uMfolozi River has been pouring into the lake all summer with potentially harmful consequences for its viability.
The approach to mechanically re-connect the Umfolozi River to the St Lucia system was to remove previously dredged separation deposits by mechanically pumping these into the sea tidal zone approximately 1km north of the original St Lucia mouth opening. It was expected that this would prevent the deposits from obstructing future mouth opening. This mechanical pumping project commenced in May 2016 but was a failure from the outset and iSimangaliso hastily altered the approach. The Park authorities had the deposit mechanically removed by a fleet of excavators and trucks and dumped in the original St Lucia mouth-opening zone.
This dumped material has now developed into an unintended dune that is continuously increasing in height, with vegetation growth. The problem is that no one knows when and if a breach will occur whilst the dune continues to become higher and more stabilized. A natural breach will now require a massive flooding event.
Resolving the issue may require a re-look at iSimangaliso’s Five-year Integrated Management Plan, in implementation since 2017, and a renegotiation of the relationships between iSimangaliso and neighbouring stakeholders.
Voices among local business, which is heavily dependent on the tourism industry, complain that the build-up of silt has led to a proliferation of reeds which is not only an aesthetic problem (preventing wildlife viewing) but threatens to choke the shallower areas of the estuary. This siltation build up and accelerated reed growth would not occur if the mouth was open to the sea, as the tidal movement would flush out silt loads and the seawater would prevent reed growth. But this may be the least of iSimangaliso’s problems.
Cutting off St Lucia from the sea raises the danger that it will turn into a fresh-water lake and lose its unique estuarine character. ‘The mangroves – which depend on a mixture of salt and fresh water – may be dying’, says one tourism operator.
Others have complained about the backing of the lake’s waters up the uMfolozi flood plain, inundating farm lands. This would not happen if the mouth were managed as a true estuary which would generally be open to the sea. The farm worst affected, Cotcane, is owned by land restitution beneficiaries, the Mapumulo family. But it is not only commercial farmers who are affected. The Sokhulu community, located at Maphelane on the southern edge of the Wetland Park, have also been inundated.
A spokesperson for the Sokhulu community was quoted in the local press last year, arguing that iSimangaliso had failed to deliver on promises to open the river mouth and relieve the flooding. ‘We have a lot of gatherings and meetings with iSimangaliso but there is no resolution’, he said.
It is easy to sympathise with the complexity of the tasks facing the park’s management. Salinity ratios have been an issue for conservationists for decades. In the 1960s, a period when the mouth was continuously open, saw hyper-salinity affect the lake, with salt levels rising above that of the ocean. The period is famous for the rescue of Lake St Lucia’s crocodile population, which was captured and airlifted to more congenial surroundings by Air Force helicopters.
There have also been periods of drought, which affect not only water levels but also the salinity of the lake. The most recent episode was in 2015, when dry weather saw St Lucia’s surface area reduced by 90 percent through evaporation. That drought was relieved between December 2015 and March 2016 when good rains saw water begin to flow into the lake again. But it was also the beginning of a stand-off between iSimangaliso and commercial farmers, which ended up in court.
In early 2016, when water levels on the floodplain reached 1.2 metres above sea level, the sugar farmers asked iSimangaliso management to breach the dune within 24-hours in accordance with both time-honoured practice and an interim court order of October 2015. Umfolozi Sugar Planters Limited says it sought the original court order ‘for the sole purpose of seeking legal clarity on the situation’. iSimangaliso management at the time effectively refused to do so and were taken back to court by the sugar farmers. However, this time around, the farmers lost their case. The High Court ruled in October 2018 that they ‘had not adequately shown that iSimangaliso failed to develop and/or implement the statutory requirements for managing the river mouth’.
ISimangaliso had commissioned considerable scientific research, especially into the mechanics of the river mouth. The consensus was that the main source of St Lucia’s fresh water was the uMfolosi River but that this had been cut off from the lake by a dredged channel and embankment along the south side of the estuary. When introduced – in the 1950s – this was considered a conservation strategy designed to prevent an influx of silt from the uMfolozi into the lake. But the desirability of this mechanism was undermined by a scientific report released in 2012, which advocated bringing uMfolozi water directly into the estuary. iSimangaliso’s Intergrated Management Plan described this strategy as ‘minimum interference, no artificial breaching and the res-establishment of the natural river course’.
The current impasse and the build-up of silt in St Lucia raises concerns about whether this decision is correct. It was based on the best available science at the time. But while scientists have no doubt described the historical mechanics of the estuary, management going forward has to be seen as an experiment. It is only consistent with the scientific method to continuously ask whether it is working and whether its assumptions are still valid.
In the meantime, questions about the health of the estuary and its longer-term sustainability are proliferating and require answers from the authorities.
The World Heritage Organisation is a proponent of ‘stakeholder theory’, which is founded on the belief that it is possible to manage relationships between conservation, community and commercial interests in a manner beneficial to all. This approach is reflected in the Integrated Management Plan, which argues that: ‘The Authority’s development and empowerment priority is to deliver tourism developments linked to land claimant co-management agreements that create jobs, stimulate economic growth and generate revenue that will contribute towards community empowerment.’
The decision to leave the mouth of the estuary to natural development is the flagship initiative of active ecological management of Lake St Lucia. The Integrated Management Plan commits iSimangaliso to on-going monitoring of the performance of the ‘hydrological, physical and ecological functioning of this important estuary system’.
Questions are however being asked among local stakeholders. iSimangaliso needs to speak out and share its views on the success or otherwise of the minimal interference approach. There are fears which need to be put to rest and good science demands maximum openness and thus communication on the matter.
- iSimangaliso was given an opportunity to respond to this article, but had not done so by last evening.
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