A Project Preparation Grant will finance a feasibility study on possible interventions to bring fresh, sediment-free water from the Umfolozi into Lake St Lucia.
WASHINGTON DC, February 4, 2009 - iSimangaliso has signed a Project Preparation Grant (PPG) agreement with the World Bank for a GEF project which aims to include addressing the hydrology and ecosystem functioning of the Lake St Lucia system. The project is producing a feasibility study and Environmental Impact Study (EIA) on possible interventions to bring fresh, sediment-free water from the Umfolozi into Lake St Lucia. Electronic copies of the Background Information Document (BID) are available on request from info@iSimangaliso.com.
Lake St Lucia, one of the Park's Ramsar sites, is currently experiencing its 8th year of drought but has recently had some relief, with more than 60mm of rain falling over the lake and some of its catchment areas last week. Furthermore, between May and early December 2008, 15 million cubic metres of fresh water entered Lake St Lucia from the Umfolozi River, providing some relief to the southern parts of the drought-stricken lake. This was made possible by sound eco-advice from Ezemvelo KZN Wildlife and the re-opening the 1960s-built Back Channel allowing relatively silt -free water to flow into the St Lucia Lake system
During this period the Umfolozi flowed weakly, and its mouth which had closed naturally, caused small quantities of water to build up behind it.
"This fresh water has helped stabilise the St Lucia system, which began to show signs of stress due to the continuing drought that began in 2001 and the ingress of sea water caused by heavy seas from Cyclone Gamede and exceptionally high tides which breached the estuary mouth in March 2007."
On December 5th, a rapid three-metre rise in the level of the Umfolozi River threatened to break open the Umfolozi River into the sea. iSimangaliso Park and Ezemvelo KZN Wildlife then deliberately breached the mouth to prevent excessive debris and harmful sediment from the Umfolozi to flow via the Back Channel into the Lake, and to avoid the risk of the Umfolozi entering directly into the St Lucia Estuary. In former years, much of the sediment would have been filtered from the Umfolozi by the large swamplands, however these were cleared for sugar cane farming from the 1930s. Water now flows unimpeded down the canalised Umfolozi River resulting in high sediment content.
The Umfolozi River mouth closed naturally on the 26 December. This once again led to the river level rising, and a further approximately 1.4 million cubic metres of fresh water flowed into Lake St Lucia via the Back Channel. By the evening of 8 January 2009 however, the level of the river had risen to the extent that it again breached the mouth naturally, to subsequently scour a relatively deep channel to the Indian Ocean which is currently flowing strongly out to sea.
The gain of more than 16 million cubic metres of silt free fresh water from the Umfolozi River over the last few months has been beneficial to the lake, which is currently under pressure from the ongoing drought. The southern section of Lake St Lucia, referred to as "the Narrows", is currently the least saline part of the lake containing approximately 4-5 parts of salt per thousand parts water- compared to the salinity of the sea being 35 parts per 1000. Salinity levels recorded in the northern reaches of the lake are very high, with measurements at Lister Point in the False Bay section of the Lake being in the region of 100 parts per 1000. This has resulted in a die-off of fish and pencil bait (stick bait) - a bivalve mollusc that lives in the mud.
The bi-annual national Coordinated Waterbird Count (CWAC), which is conducted, is currently underway, and Park staff and visitors have been seeing significant flocks of flamingos, pelicans and waders in various parts of the lake in the last few weeks. The vegetation on the margins of the lake continues to be fed by groundwater seepage. This seepage is a welcome source of fresh water for the wildlife in the Park and has been improved with the removal of 6 500ha of pine plantations from the Eastern Shores.
On the Western Shores, although 9000ha of pines plantations have now been cleared, fresh water is scarce. The Western Shores section does not have the deep sands of the Eastern Shores, and hence does not have similar groundwater supplies. If the high temperatures and poor rainfall continue, contingency plans may need to be implemented to supplement fresh water for wildlife.
The SA Weather service long range forecast indicates above-normal rainfalls for iSimangaliso Wetland Park in February-May. This much needed late summer rain is eagerly awaited.
For more information:
Roland Vorwerk, Acting Media Officer , iSimangaliso Wetland Park Authority, 082 466 1251