Urgency needed to save the St Lucia estuary
The St Lucia estuary is in a critical condition. What was until recently South Africa’s greatest estuarine system has been sealed from the ocean since 2002 with only a brief breach between lake and ocean for five months in 2007. The problem is result of management decisions human intervention and the obvious solution – an artificial breach – is a tried and tested management technique successfully applied by Ezemvelo KZN Wildlife over decades. This management model needs to be urgently reintroduced.
Estuaries are very special environments in which life has adapted to a changing mix salty seawater and freshwater. Such environments are associated with mangroves and other flora and fauna adapted to thrive under conditions of varying salinity. A healthy estuary is typically clean and mud-free thanks to the scouring effects of ocean tides. Like all estuaries, St Lucia had a thriving fish and bird population, complemented by a big population of hippos and crocodiles. The estuarine prawn nursery has previously been described as the ‘most productive’ on the South Africa coast.
But the St Lucia estuary has drowned in mud. This has been deposited by the Mfolosi river through four points of entry including the three back-channels which were closed by Ezemvelo specifically to prevent increased sedimentation. The river was artificially linked to the estuary in an attempt to deal with drought conditions prior to 2016, a problem aggravated by intervention which prevented any water entering Lake St Lucia within the mouth area. These conditions provided the opportunity to remove the ‘dredger spill dune’, utilising the material to construct a ‘dam wall’ completely separating the ocean and the lake. This was a huge mistake and it cannot be understood how consultants, management and scientists allowed it to happen.
St Lucia was proclaimed a United Nations Educational Scientific and Cultural Organisation (Unesco) World Heritage Site in 1999. The proclamation includes much more than just the estuary and covers a system of lakes and wetlands which run up the Zululand coast to the Mozambique border. But the 70km long estuary was singled out by Unesco as one of three ‘outstanding natural phenomena’ which justified World Heritage status. Unesco remarked at the time:
‘One (of the outstanding features) is the shifting salinity states within Lake St Lucia which are linked to wet and dry climatic cycles with the lake responding accordingly with shifts from low to hyper-saline states’.
The problem is that there is simply no longer a functioning estuary. The unique estuarine features of Lake St Lucia have evaporated like dew before the morning sun, leaving an expanse of mud and reeds, and in some areas a much less diverse fresh-water lake. A report to the Living Lakes Foundation last year summarises the present condition of the area:
‘Salt-reliant plants have died including the mangroves and organisms dependent on them have become extinct. Excessive reedbeds have flourished and expanded in these fresh-water conditions … the natural pendulum shift between fresh and saline water has ceased to function … fish that rely on the estuary and lake to spawn are therefore unable to do this while other fish that need to return to the ocean are landlocked’.
Since its proclamation, the estuary has been under the management of the iSimangaliso Wetland Authority, a purpose-established agency which reports directly to national government. It had previously been managed by the provincial conservation authority, Esemvelo Wildlife, which had taken a very active approach to managing the mouth. Through dredging, the mouth was kept open ninety-two percent of the time, thereby preserving its estuarine condition. The National Research Foundation’s Estuary Information System described the condition as ‘good’. Under iSimanagaliso however the policy of not dredging and thus keeping the mouth closed has been the default management policy.
The estuary was first sealed from the sea in 2002 to protect it from spillage from a shipwreck. The 31 000 ton freighter Jolly Rubino had caught alight and then gone aground dangerously close to the estuary. The decision to artificially close the estuary mouth was widely approved at the time. However, although it was stated that the new berms and closures would be removed following clearance of the potential oil spill, this never happened. The estuary remained shut. Damaging though this was, the most harmful intervention was yet to happen.
The Mfolosi mouth had been kept separate from Lake St Lucia, by dredging both at the mouth and further back, in ‘the narrows’ since 1952. Large amounts of dredger spoil were deposited in the southern part of the estuary, in the process reinforcing the levee which redirected the river. The decision was taken to remove the levy and pump the dredger spoil into the sea to be dispersed by the current. The iSimangaliso Wetland Authority management of the time did not like the existing arrangement, referring to disapprovingly to ‘excessive dredging in the narrows in a 2011 Information document.
Funding was obtained from the World Bank’s Global Environmental Facility (GEF) which put up US$9 million between 2009 and project closure in 2017. Other funding came from the South African government and other donors, notably the government of the Netherlands. Although the funding was designed to cover many aspects of sustainable development, including scientific studies, education, community and small business development, the central focus was on removing the dredger spoil. But this part of the programme was a disaster.
The process of mechanically pumping the dredger spoil into the sea commenced in May 2016 and immediately ran into problems. The task was beyond the capacity of the equipment available and the situation was not helped by iSimangaliso’s refusal to allow the contractor to abstract fresh water to flush the spoil down the 300 mm pipe. Attempts to pump the spoil were quickly abandoned and mechanical excavators deployed instead.
The problem was that instead of being pumped into the sea to be dispersed by currents, the dredge spoil was dumped on the breach at more-or-less the point where the estuary mouth would ordinarily breach. The result is that the estuary and the sea are separated by an artificial wall which nature is highly unlikely to breach without human assistance. A satisfactory explanation for transporting the spoil only halfway to its obvious dumping point in the ocean was never given by either iSimangaliso or the World Bank. Unesco too has been entirely silent on the matter.
The volume of dredge spoil dumped on the beach is easy to underestimate especially if viewed from ground level on the Lake St Lucia side. But according to the World Bank’s 2017 Project Closure document the volume dumped totalled 140 million cubic metres. If this volume of mud and sand were arranged in a cube, it would be one hundred and twelve metres along each side. That is approximately one third of the height of the Empire State Building in New York and almost exactly the same height as one of Durban’s tallest buildings, 320 West Street.
The initial hope was that a natural breach, brough about by summer flooding, would re-link the estuary to the sea. But the volume of spoil is too great to make this a realistic expectation. Instead, each wet season exacerbates the problem by dumping more sediment, thus reducing the velocity of floodwaters attacking the artificial wall from the Mfolosi River side.
Those counting on a natural breach have been reduced to suggesting that the solution is a replay of 1984’s Tropical Cyclone Demoina which washed away much beachfront and the dredger harbour in the estuary. But Demoina is described as a ‘once-in-a-hundred-year storm’ and was hugely destructive. The cyclone killed 242 people (60 in South Africa), left tens of thousands of poor rural people stranded and left damage valued (then) at R100 million. Hoping for a replay is both morally indefensible and no sort of management strategy whatsoever.
St Lucia is said, by the authorities, to represent eighty percent of the sub-tropical estuarine environment in Southern Africa. But this rare and beautiful natural phenomenon is not the only casualty of a management mis-step. The local tourism industry is heavily dependent on offering an estuarine experience, involving viewing hippos and crocodiles, especially to foreign tourists. Prior to the introduction of travel restrictions to combat Covid-19, foreign tourists made up eighty percent of the market. Without this offering, many of the 1 291 direct and nearly 7 000 indirect local tourism jobs are at risk. Many local people are already struggling to put food on the table. Failure to revive the estuary would come as a final blow to many.
Besides jobs, there has been considerable transformation in the local tourism industry. Entrepreneurs like former KwaZulu-Natal MEC for Economic Development Mike Mabuyakhulu have bought into local ventures. These emerging businesspeople stand to lose as much as more established businesspeople.
Also at risk are upstream agricultural activities. The backing up of the Mfolosi River behind the artificial wall has affected commercial sugar farms through flooding. Farmers affected include three land-restitution beneficiaries. The Sokolu community at Maphelane on the southern edge of the estuary have also been inundated. They are unable to plant vegetables and their economic and social future hangs on a knife-edge.
Decisions about the mouth of the St Lucia estuary and its interaction with the Mfolosi River have been based on scientific research. The objective was ‘to retore the natural hydrological and ecological functioning of this important system’. There is no reason to doubt the integrity of these studies but the subsequent management measures have turned out to a recipe for disaster. There is no need to wait for a further round of scientific investigation. An artificial breach is the obvious answer. Restoring the actual existence of the St Lucia estuary depends on it. To achieve this, the Ezemvelo KZN Wildlife model must be reinstated. There are academics, conservationists and other professionals available with extensive practical experience who should be allocated the task of opening and managing the St Lucia mouth as soon as possible.
SAVE ST. LUCIA is a grouping of concerned citizens and local businesses in the town of St Lucia