Source to Sea Programme

Orange River Mouth Project

The Ecosystems Approach
The Endangered Wildlife Trust (EWT) is the South African implementing partner of the USAID/IUCN programme on applying the Ecosystems Approach (EA) in the Orange-Senqu basin. The first tier of the EA recognises the importance of holistic, nature-friendly, ecosystem management and planning as an integral part of Integrated Water Resource Management (IWRM). The second tier, promotes the importance of stakeholder engagement, participation and partnerships in applying the EA and provides opportunities for negotiation, dialogue and consensus building over water management techniques that meet the needs of communities, the economy and the environment.

The Orange River Mouth (ORM) is one of few areas of sheltered shallow water along southern Africa’s arid Atlantic coastline. It is a transboundary site, forming the international border between South Africa and Namibia. It is South Africa’s second most important estuary for biodiversity conservation and the sixth most important coastal wetland in southern Africa for birds and fish. Historically the ORM supported vast bird populations, reaching 26 000+ individuals comprising of 57 species in the 1980s. Fourteen of the bird species are listed as rare or threatened with extinction. Thirty-six species of fish representing 19 families have been recorded at the ORM of which several species are threatened or endemic, while 31% of the fish recorded are dependent on estuaries for their survival. The ORM falls within the Desert Biome, with three vegetation types: Arid Estuarine Salt Marshes (NFEPA Endangered wetland), Alexander Bay Coastal Duneveld (Critically Endangered) and Western Gariep Plains Desert. In recognition of the estuary’s ecological significance both locally and internationally, the Orange River Mouth was bestowed Ramsar status in 1991. However in 1995, the same year that the Namibian portion was granted Ramsar status the South African portion of the Orange River Mouth was placed on the Montreux Record; a list of degraded Ramsar wetlands in need of urgent conservation action.

Figure 1. The extent of the basin with dams and estuary indicated

Collapse of the Salt Marsh
Human disturbance of the estuary commenced as far back as 1929 when mining and mouth breaching began. In the 1960s, dams were constructed leading to a reduction in small floods required to flush the salt marsh of excess salts. During the same period, tidal exchange was cut off by the construction of a beach access road reducing ecological connectivity. Over the following 20 years disturbances escalated; more dams were built, the inflow of fresh water was largely eliminated through the construction of agricultural levees and the diversion of flood channels, wastewater disposal into the estuary increased salinity, and dust from slimes dams began to smother vegetation. In 1988 the salt marsh collapsed; large floods led to scouring and silt deposition, the standing water – unable to drain due to the beach access road – killed off 90% of the already weakened salt marsh habitat and left the soils in a hypersaline condition unsuitable for seed germination.

Table 1. Sequence of events, leading to the collapse of the salt marsh

Year Event
1929 Mining & mouth management.
1960 Beach access road & causeway construction.
1964 Small floods (1:2 and 1:5) + high spring tides flooded marsh.
1968 Dams built: River Flow Regulated <60% reference condition. Small floods <85%
1974 Channels diverted via agricultural levees cutting off major channels to floodplain.
1980 Disposal of mine wastewater from slimes increases salinity of the floodplain.
1986 Windblown dust from slimes dams begins to significantly smother vegetation.
1988 Flood breaches embankment and scours salt marsh. Standing water and sediment deposits kill lead to salt marsh collapse.
1993 & 1998 Mouth closes, back-flooding occurs. Beach berm prevents drainage.
2004/2005 Cotula coronopifolia begins to recolonize post beach berm breach (1997) by Working for Wetlands.


In the 90s the habitat’s poor condition worsened when the mouth closed (1993 & 1998). Back-flooding occurred but the berm again prevented drainage increasing the salt content through evaporation further. In 1997 and again some years later in 2004/5, Working for Wetlands (WfW), undertook to breach sections of the beach berms in order to restore some of the ecosystem’s lost connectivity. The health of estuary backwater has subsequently improved while some areas of fresh water intrusion allowed the recolonization of Cotula coronopifolia (bright green)- giving hope that with freshwater re-connectivity the salt marsh can be rehabilitated.

Figure 3. Changes in the condition of the salt marsh between 1937 and 2016

The Importance of Estuaries and Associated Habitats

What is an Estuary?
Simply put, an estuary is the place where the river meets the ocean. Saltwater and freshwater mix to create a unique habitat which is neither river nor ocean. An estuary is bounded by the river mouth on the seaward side and ends where saltwater no longer mixes with fresh water. Estuaries are dynamic ecosystems, influenced by changing tides and river inflows. Most estuaries have an associated flood plain which becomes inundated during flooding events or during ocean storm surges.  The inflows of both sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.

Ecosystem Services
Ecosystem services are direct or indirect contributions that ecosystems make to the wellbeing of human populations. Estuarine and costal ecosystems (ECEs) such as: coral reefs, seagrass beds, salt marshes, mangroves, and sand beaches and dunes, are some of the most utilised and threatened natural systems, suffering significant declines worldwide. The global decrease in ECEs has been known to affect at least three critical ecosystem services: the number of viable fisheries; the provision of nursery habitats; and filtering and detoxification functions.

Estuarine and coastal ecosystems exist at the interface between watersheds, land and the coast resulting in cumulative benefits which are more significant and unique than the services provided by any single ecosystem. The loss of biodiversity, coastal vegetation and function of these ecosystems weakens these systems leading to biological invasions, declining water quality, reduced protection from flooding and storm events and a decline in many provisioning services.

The collapse of the ORM salt marsh is a symptom of a dysfunctional ecosystem; the natural dynamics and interactions have been interfered with to the extent that the estuary no longer functions properly, limiting the services it can provide. And while improbable that ORM could ever be fully restored, urgent conservation action is needed to reinstate some of the functioning of this rare and unique transboundary Ramsar site.

Project Impact

In line with the Ecosystems Approach, this project aims to protect this unique estuary through holistic and sustainable ecosystem management practices while building partnerships, engaging stakeholders and fostering collaboration. As this is an integrated approach to ecosystem conservation, we are contributing towards many of the Sustainable Development Goals (SDGs) in under-resourced regions that are particularly vulnerable to climate change and resource exploitation. Below are the SDGs that this project addresses:

The specific impacts we are working towards within this partnership are:

  1. Improved catchment and water management practices that ensure the greatest degree of water security and resource protection under changing climatic conditions.
  1. The formalised protection and restoration of the second most important estuary in South Africa
  1. An informed and engaged catchment community where the youth are included in integrated water resource management and are ready to adapt to the potential risks of climate change.
  1. An active citizen science network, collecting data on river condition and flows at the WESSA EcoSchool in the catchment. This will feed into a local monitoring programme, in partnership with provincial and national conservation agencies.

Due to the transboundary nature of the ORM, and the importance of its role as a fish nursery, the beneficiaries extend far beyond its geographical boundaries.

  • Primary –Provincial and national departments involved directly at the site; local schools. The Alexander Bay and Port Nolloth Communities.
  • Secondary – tourists; recreational users; adjacent Richtersveld communities; government and other stakeholders (including Namibia); universities; researchers; bird enthusiasts; fishing community.
  • Tertiary/Others – interested parties; general public; international community (Site of International Importance)

Project Highlights to Date

Conservation planning

We have completed a LiDAR survey, which will not only be utilised to finalise the proclamation of the site by delineating the boundary of the site (current boundaries are inaccurate), but will also provide critical data required for strategic rehabilitation planning. LiDAR uses lasers to acquire fine scale data used in Digital Elevation Modelling (DEM). The DEM can be used to determine areas of soil build up and to identify areas where water flow can be reconnected. This is crucial to restoring the ecosystem functioning of the estuary.

Ecological Monitoring

The EWT reinitiated biannual bird counts and initiated monthly bird counts and monthly water quality testing. These activities were in collaboration with the Northern Cape Department of Nature Conservation (DENC) and the National Department of Water and Sanitation (DWS). The EWT also took part in an aerial survey in collaboration with the Bateleurs, a fish survey in collaboration with the Department of Agriculture Forestry and Fisheries (DAFF) and assisted DENC with river patrols.

These monitoring efforts are critical to the long term ecological understanding of the site. Monitoring should be continued in order to detect trends and to understand better the biotic-abiotic interactions. These baseline data are also critical to understanding the effectiveness of interventions in future such as further breaching of the beach access road, mouth machinery removal and the construction of the proposed Vioolsdrift dam.

Stakeholder Engagement and Partnership Building
One of the key successes of this project, in line with the second tier of the Ecosystems Approach, has been to raise the awareness and profile of this internationally important Ramsar site by engaging stakeholders both nationally and locally. The ORMIMC, mentioned earlier, was in place for over 15 years. However, due to its interim nature none of the stakeholders were in a position to implement any activities on the ground.

This project has allowed implementation to take place and has spurred further interest and action from DENC, the Department of Environmental Affairs (DEA), the Orange-Senqu River Commission (ORASECOM), Ramsar – South Africa, DWS, Alexkor, local municipalities and EcoSchools. The EWT has presented and a number of conferences and strengthened relationships with organisations such as Conservation South Africa (CSA) and the Wildlife and Environment Society of South Africa (WESSA).



Grant Smith: Project Field Officer email