Special Edition News Release One mouth for Lake St Lucia system

The strategy to allow the uMfolozi and Lake St Lucia estuary mouths to join to form a combined mouth is progressing well. The linking of the two systems via the beach spillway resulted in approximately 16.4 billion litres of fresh water reaching the Lake St Lucia estuary and lifting water levels at the end of the dry winter period. The early spring rains and natural breaching of the uMfolozi mouth, which resulted from the one-in-five-year flood, have created a marine connection for the system. The recent events are both natural and positive and are part of the much broader long term strategy to restore estuarine function to this important nursery for fish and invertebrates. Key to this is to allow these systems to function as naturally as possible. With the Lake St Lucia and uMfolozi systems joined, modelling shows that their combined mouth will be open more often than it is closed. However, it is unlikely that there will be a rapid recovery of the Lake St Lucia system - one of South Africa’s most important estuarine systems and Africa’s largest estuarine lake (approximately 32 000 ha). Together with reduced water inflow from nine years of below average rainfall, the lake has had little or no water from the uMfolozi river for the past 60 years. The Lake St Lucia system requires large volumes of water before it is able to function within a range considered to be natural and indicative of a healthy system. Over the next two to three years the level of the water in Lake St Lucia will be highly dependent on rainfall, the amount of which will determine how quickly the level rises. This means that a large flood could fill the system quickly or that under average rainfall conditions, it could take a number of years. Underpinning this management strategy implemented by iSimangaliso in partnership with Ezemvelo KZN Wildlife, is the work undertaken through the iSimangaliso GEF project. In its final stage, the Project is investigating and formulating a long term solution to restore, as far as possible, the natural hydrological and ecological functioning of this important system. The aim is the ecological restoration of Lake St Lucia and the protection of iSimangaliso’s World Heritage Site values such that ongoing human intervention is no longer needed or minimized. Phase 1 of the GEF project included a scientific review workshop attended by 41 scientists including hydrologists, estuarine ecologists, estuarine hydrodynamic specialists, social scientists and geologists, and stakeholder and public meetings. This research collaboration has already paid off with the new science guiding the ‘combined mouth’ strategy for Lake St Lucia that is currently being implemented. iSimangaliso will continue to interact with and keep stakeholders and interested parties informed of the state of Lake St Lucia and progress made with the GEF Project. (For more information visit www.iSimangaliso.com and download ‘Lake St Lucia: understanding the problem and finding the solution’.) Andrew Zaloumis, Chief Executive Officer, iSimangaliso Wetland Park

Beach spillway transfers water The beach spillway, created to expedite the reconnection of the uMfolozi River with the Lake St Lucia estuary, was opened on 6 July 2012. (For more information on iSimangaliso’s strategy to let the uMfolozi River and Lake St Lucia rejoin refer to the textbox at the end of the document: ‘2011 New lake St Lucia Estuary Management Strategy’). Between 6 July and 7 September 2012, the water flow through the spillway, as well as the water levels and salinity within the Lake St Lucia estuarine system have been monitored closely by park staff. The monitoring has indicated that the spillway was extremely successful in transferring a large volume of water from the uMfolozi catchment to Lake St Lucia while the mouth was closed.

Plate 1: The beach spillway transferred an estimated 16.4 billion litres of water from the uMfolozi River to Lake St Lucia over 8 weeks. The amount of water transferred by the spillway during this period was dependent on rainfall in the uMfolozi catchment and by the end of winter the volume of water flowing down the uMfolozi river was significantly reduced. Analysis of the flow data has enabled us to estimate that the total volume of water transported by the beach spillway was approximately 16.4 billion litres while the uMfolozi river mouth was closed

Plate 1: The beach spillway transferred an estimated 16.4 billion litres of water from the uMfolozi River to Lake St Lucia over 8 weeks. The amount of water transferred by the spillway during this period was dependent on rainfall in the uMfolozi catchment and by the end of winter the volume of water flowing down the uMfolozi river was significantly reduced. Analysis of the flow data has enabled us to estimate that the total volume of water transported by the beach spillway was approximately 16.4 billion litres while the uMfolozi river mouth was closed

Plate 2: The beach spillway was substantially widened by the early spring rains. It connects the uMfolozi, Lake St Lucia and the sea. This photograph was taken during the spring high tide on 17 September 2012 Once the uMfolozi River breached, water flowed southwards from the Estuary through the beach spillway and out through the open mouth. This occurred until the water level in the Estuary dropped to levels below the base of the beach spillway. In the final account, the water level in the Narrows has risen by a total of 25cm, with a corresponding increase in the rest of the Lake, and levels are the highest they have been since November 2011. In this configuration it is likely that the beach spillway will continue to intermittently connect the uMfolozi, Lake St Lucia and the sea. The extent to which this will occur is dependent on sea condition and wave action, the water levels in the Lake and the uMfolozi river and tidal influence

Since these first spring rains broke the winter dry period further rains have been received over the weekend of 14–16 September 2012. These have resulted in good rainfall being received across iSimangaliso (see table 2 below)

Salinity values of Lake St Lucia These two rainfall events have brought much needed water to fill wetlands and pans, and to recharge groundwater levels. Rivers like the uMkhuze, uMphathe and Nyalazi that flow directly into the Lake are also flowing strongly. Combined with the effect of direct rainfall on the Lake, salinities throughout the system have decreased substantially with the highest salinity values in the north of the system at 53 parts per thousand (Listers Point) and 2 parts per thousand in the Narrows

Salinity values of Lake St Lucia These two rainfall events have brought much needed water to fill wetlands and pans, and to recharge groundwater levels. Rivers like the uMkhuze, uMphathe and Nyalazi that flow directly into the Lake are also flowing strongly. Combined with the effect of direct rainfall on the Lake, salinities throughout the system have decreased substantially with the highest salinity values in the north of the system at 53 parts per thousand (Listers Point) and 2 parts per thousand in the Narrows

For example, flamingos are currently found in the northern parts of the lake in large numbers indicating the presence of shallow brackish water that supports the type of food they eat. White pelicans are also present in large numbers and have bred successfully with more than 700 large chicks found in this sheltered breeding colony.

here is also a large number of bird species using the intertidal areas at the open mouth for feeding and resting. Migratory waders such as curlew sandpipers, whimbrels and ringed plovers have recently arrived from the Palaearctic for the summer. They are feeding on invertebrates living in the sand and mudflats, such as worms and small crustaceans. Pelicans and herons are feeding in the shallow water on fish and prawns. Large flocks of terns, predominantly swift terns but also including little terns, Caspian terns and the rarer vagrant Sooty terns are also found in large numbers. The sooty tern has drawn a lot of interest from bird-watching enthusiasts and has been reported on the South African Rare Bird report over the past few months.

Where to now? The strategy to allow the uMfolozi and Lake St Lucia estuary mouths to join to form a combined mouth is progressing well. The linking of the two systems via the beach spillway resulted in approximately 16.4 billion litres of fresh water reaching the Lake St Lucia Estuary and lifting water levels at the end of the dry winter period. The early spring rains and natural breaching of the uMfolozi mouth, which resulted from the one-in-five-year flood, have created a marine connection for the system. The recent events are both natural and positive and are part of the much broader long term strategy to restore estuarine function to this important nursery for fish and invertebrates. Key to this is to allow these systems to function as naturally as possible. With the Lake St Lucia and uMfolozi systems joined, modelling shows that their combined mouth will be open more often than it is closed. However, it is unlikely that there will be a rapid recovery of the Lake St Lucia system - one of South Africa’s most important estuarine systems and Africa’s largest estuarine lake (approximately 32 000 ha). Together with reduced water inflow from nine years of below average rainfall, the lake has had little or no water from the uMfolozi River for the past 60 years. The Lake St Lucia system requires large volumes of water before it is able to function within a range considered to be natural and indicative of a healthy system. Over the next two to three years the level of the water in Lake St Lucia will be highly dependent on rainfall, the amount of which will determine how quickly the level rises. This means that a large flood could fill the system quickly or that under average rainfall conditions, it could take a number of years. Underpinning this management strategy implemented by iSimangaliso in partnership with Ezemvelo KZN Wildlife, is the work undertaken through the iSimangaliso GEF project that is investigating and formulating a long term solution for the hydrological and ecological functioning of the Lake St Lucia system. The aim is the ecological restoration of Lake St Lucia and the protection of iSimangaliso’s World Heritage Site values such that ongoing human intervention is no longer needed or minimised. The first phase of this component is complete and involved the analysis of the possible management options that will promote restoration of the system. These options have been presented for comment and input to scientists and other stakeholders, such as local communities and ratepayers, the floodplain sugar farmers, the tourism operators, government, NGOs and other interested parties. The stakeholder events included a scientific review workshop attended by 41 scientists including hydrologists, estuarine ecologists, estuarine hydrodynamic specialists, social scientists and geologists. The project is in its final phase, which includes the appointment of the team of specialists to provide detailed analysis of the selected options. This process will take ecological, social, financial, political and economic considerations into account, and will include environmental authorisation. The consultants’ work is expected to take 12 months. A portion of the GEF budget has also been set aside to finance the implementation of the preferred option. iSimangaliso Wetland Park staff and scientists will continue to monitor the status of the system and its response to the current management intervention iSimangaliso will continue to interact with and keep stakeholders and interested parties informed of the state of Lake St Lucia and progress made. (For more information www.iSimangaliso.com and download ‘Lake St Lucia: understanding the problem and finding the solution’.).

2011 New Lake St Lucia Estuary Management Strategy Sixty years of manipulation and separation The Lake St Lucia system is one of the most important estuaries in South Africa and the largest of only three estuarine coastal lake systems in the country, with a water surface of 300 km2 and a shoreline of over 400 km. It represents over 80% of the estuarine area of the southern African sub-tropical region and 60% of the estuarine area of the country, making it the most important nursery ground for juvenile marine fish and prawns along the east coast. Lake St Lucia, however, is facing serious hydrological problems. For the most part of the last decade there has been below average rainfall and very little water from the system’s five rivers has flowed into the lake. This has also resulted in the Lake St Lucia mouth remaining closed, which has meant the system has not functioned as an estuary. As a result, fisheries, such as the inshore line fish and crustacean fisheries, have been negatively affected. While changes in the catchments of these rivers have affected the amount and quality of water entering the lake, the major impacts on Lake St Lucia have arisen through human intervention in the uMfolozi catchment, which is the largest catchment of the Lake St Lucia system. Of particular significance are measures implemented to support sugar cane farming on the uMfolozi floodplain; namely, the removal of the swamp vegetation on the floodplain, the canalisation of the uMfolozi River and the separation of the uMfolozi and Lake St Lucia systems. The uMfolozi River was separated from Lake St Lucia in the early 1950s and kept separate through the use of dredgers and the building of berms. This has interfered with natural mouth dynamics and resulted in a reduction of freshwater inflow to the system. (Visit www.iSimangaliso.com to download ‘La ke St Lucia: understanding the problem and finding the solution’.

Owing to concerns about sediments from the uMfolozi being deposited in the Lake St Lucia estuary, the decision to maintain separate mouths for the uMfolozi and Lake St Lucia remained in place for the last 60 years. Recent research projects registered with iSimangaliso have shown that the risk posed by sediments to the Lake system may have been overstated. Estuarine scientists have pointed out that the sedimentation of estuary mouths is a natural process, and that these sediments are an important part of maintaining the habitat that supports estuarine animals and other species. Over the last decade public concern has heightened and the different views of residents, farmers, fishermen, tourism operators, tourists and visitors, local communities, scientists, nature lovers and conservationists have generated constructive debate. Collaboration with scientists working in the Lake St Lucia mouth and estuary has already paid off, informing iSimangaliso’s current management strategy. This document follows on from the background information document ‘Lake St Lucia: understanding the problem and finding the solution’ (BID2011/07) published in July 2011 (Visit www.iSimangaliso.com to download ‘Lake St Lucia: understanding the problem and finding the solution’.) and should be read in conjunction with it. Together, these documents aim to build understanding of the context and provide updates on the status of the system and progress made through iSimangaliso’s GEF (Global Environmental Facility) project. Lake St Lucia and the uMfolozi River rejoin In 2011 iSimangaliso publicised its strategy to let the uMfolozi River and Lake St Lucia rejoin in a bid to restore the functioning of South Africa’s largest estuarine system. This strategy is based on the work and input of scientists working in the system, feedback from a GEF project scientific review workshop attended by 41 scientists and a Water Research Commission funded workshop organized by the Consortium for Estuarine Research and Management (CERM). The uMfolozi river eventually closed naturally within 300m of the Lake St Lucia mouth in early July 2012 after its northward movement from near Maphelane in the south towards Lake St Lucia Estuary. In anticipation of this closure, iSimangaliso, together with Ezemvelo KZN Wildlife, established a beach spillway between the two mouths during early March 2012. The spillway was prepared as far west on the beach as possible along a route previously followed by the uMfolozi River. Construction involved the removal of old dredger spoil and marine sediments. The final stage of constructing the spillway was left until the uMfolozi mouth closed. On 6 July 2012 the spillway began functioning allowing for water to flow into the Lake St Lucia system through the dry winter period. Maintenance and final preparation of the spillway resumed in earnest on 2 July 2012 and the removal of a sand plug of artificially created dredger spoil between the uMfolozi river and Lake St Lucia system occurred on 6 July 2012 (For more information see Newsflash No: 2012.07.09 ‘Link between uMfolozi river and Lake St Lucia system restored after 60 years.’). This formally re-linked the two systems which had been separate since 1952.