The current state of the Durban Metropolitan Area's (DMA) freshwater resource is producing a corresponding loss of biodiversity and ecological functions of certain rivers and estuaries. Poor water quality in these rivers and estuaries may also result in a loss of recreational and tourism opportunities and, in extreme cases, threats to human health. The silting up of Durban Bay results in the need to carry out costly, and ecologically sensitive dredging to maintain the operations of the port.

Potential water shortages for potable and industrial supply
Water consumption in the DMA has increased considerably over the last 50 years. If current consumption patterns continue, water demand in the city will outstrip supply, probably within the next 15 to 20 years. The Umgeni is the only river in Durban which can provide significant quantities of potable water to the city. The full potential of this river has, however, already been harnessed by its four dams (Nagle, Midmar, Albert Falls and Inanda) . In order to avoid shortages of water supply, practical conservation measures i.e. demand management, will need to be introduced as a first critical step. In addition, the optimum manner in which to harness water from river basins outside the metropolitan area, such as the Umkomaas River basin, is already being investigated.

Loss of biodiversity
A number of activities interfering with the natural functioning of rivers have resulted in a reduction of the number and diversity of species present in the DMA's rivers and estuaries. The release of water from dams and river canalisation have resulted in the rapid movement of sediments from the catchment to the estuary. These sediments smother river beds and estuaries resulting in the loss of habitat. Nutrient enrichment, oxygen depletion and heavy metal contamination have all reduced the species present in the DMA's rivers although, as yet, not to a significant degree. Changes in river flows have altered the natural pattern of opening and closing of estuarine mouths. This disrupts the recruitment of marine species and hinders the movement of species into and out of the estuary. In some cases it also reduces the ability of the system to flush out pollutants.

Loss of recreational and tourism opportunities
The rivers and estuaries in Durban potentially provide a wide range of recreational activities including swimming, fishing, boating and bird watching. These are attractive to residents and tourists alike. Many of these opportunities are being lost through the contamination of water and the silting up of river beds and estuaries.

Threats to health
Bacterial contamination of some estuaries poses a threat to the health of DMA residents as well as visitors who participate in full contact reactional activities. Bacterial contamination of rivers is also a health threat to those reliant on direct river water supply.

Silting up of Durban Bay
The high silt loads in the rivers discharging into Durban Bay has resulted in the silting up of its upper reaches. This silt needs to be removed on a regular basis, through dredging, to ensure the continued operation of the Durban Port. Such an exercise is very costly. It also has environmental implications through the impacts of dredging and disposal of spoil at sea.

Reduction in the purification function of rivers
The DMA's rivers play an important purification role in breaking down waste products discharged into them. This assimilative capacity has been reduced with the change of flow regimes (reduced flushing and dilution potential) and by conversion of the sandy river substrate to a permanent concrete base.