The water courses of the Upper Swakop River and its tributaries drain through the City of Windhoek and Okahandja Town. The CAN is supplied with water from the Upper Swakop Basin (part of the Swakop River catchment upstream of the Swakoppoort and Von Bach dams). Windhoek, Okahandja and a large number of scattered industries lie within the Upper Swakop Basin and they contribute significant water pollution loads into some of the source dams.
While considerable attention has been devoted to the optimization of the quantity of water from these dams, little is actually done with regards to the protection of the quality of the sources of water in this Basin. The CAN is facing a water supply crisis due to the increasing pollution of the Swakoppoort Dam, one of the major water sources. If this situation is allowed to continue, the water security for the Khomas Region, as well as parts of Erongo and Otjozondjupa Regions will be compromised with resultant negative impacts on the economy of the country.
The impact of upcoming industrial developments within the Upper Swakop Basin will further compromise the adequacy and quality of water, as well as likely compound the water pollution (especially algal blooms) that could render the Swakoppoort Dam unfit as a drinking water source, or expensive and difficult to treat.
The Swakoppoort Dam water is hypertrophic, while the Goreangab Dam water is no longer fit to be used as source water at the Goreangab reclamation plant. Instead, treated effluent from the Gammams sewage treatment plant is preferred to be used at the reclamation plant.
The risk of losing Swakoppoort Dam due to pollution, as part of the integrated three-dam system supplying the CAN, will compromise the security of water supply to the CAN as well as hurt the economy.
Water Supply Quality
The supply of water to the CAN from the dams, and the optimum operation of the dams are often influenced by the water quality and total evaporation from each dam. Studies on ortho-phosphate (inorganic phosphate) as the indicating parameter revealed that the Von Bach and Swakoppoort dams are eutrophic and hypertrophic, respectively. Furthermore, the research revealed that Swakoppoort Dam, with the worst water quality, was mainly dominated by blue-green algae. The dominant blue-green algae are the Anabaena and the Microcystis, which are responsible for taste and toxic substances, respectively.
Areas in the proximity of the Ujams ponds (within the Klein Windhoek River) and those downstream of Goreangab Dam are showing signs of pollution. Both areas show high values of total phosphate (TP) and in addition, the area in the proximity of the Ujams ponds showed very high values of dissolved organic carbon (DOC).
The TP for the Swakoppoort Dam averaged 0.3 mg/l, which is much higher than the United States Environmental Protection Agency (EPA) recommended values of 0.1 mg/l for the reduction of algae bloom and assurance of a healthy water body. It was clear that there are activities within the Upper Swakop Basin that are contributing to high values of DOC and TP.
Water Supply Quantity
In view of the economic importance of the CAN, several efforts have been made to ensure the availability of water, in terms of quantity, for both current and future demands. How to maintain the water supply security for the CAN at a level where at least 85% of the water demand can be supplied in 99 out of 100 years is a current area of study. To achieve this level of security, an investigation in 2003/04 identified measures to be undertaken to ensure that the targeted supply security is reached. These measures are mainly related to creating infrastructure enabling artificial recharge and abstraction from the Windhoek Aquifer. Few of these measures have so far been implemented, with the result that the targeted level of water supply security for the CAN is currently not being achieved.