Coastal water quality along Cape Town’s coastlines has seen some improvement in recent years. Figures 5 and 6 highlight the adherence with coastal water quality guidelines on the False Bay and Atlantic coastlines between 1992 and 2016. In the past decade, the False Bay coast has met the guidelines on fewer occasions than in the previous decade. Adherence with the strict guideline was very low in 2008 and 2014, while adherence with the relaxed guideline was generally better. The Atlantic coast had significantly better adherence levels than the False Bay coast and generally experienced slight improvements in both strict and relaxed targets with the DWS guidelines. The Atlantic coast only experienced a significant decrease in adherence in 2014, similar to False Bay.
Map 9 shows the adherence to DWS guidelines for each beach in 2016. Adherence with coastal water quality guidelines can be explained by understanding the geographical and climatic factors of the coastline, as well as the social geography of the surrounding residential areas of the coastline, among other factors such as infrastructural development.
Geographical and climatic factors result in certain areas being susceptible to developing poor water quality. False Bay is particularly sheltered due to its large bay area. Low wind speeds and weak currents, particularly in winter, result in reduced mixing and circulation in the sheltered area of False Bay. This is particularly marked along the Strand to Gordons Bay coastline, Fish Hoek and Simon’s Town. Reduced mixing and circulation in these areas results in stagnation and trapping of poor-quality water close to the shoreline.
The area bordering the False Bay coast is the most densely populated, with both formal and informal settlements occupying the majority of all available land. The density of these areas, coupled with ageing storm-water and sewage infrastructure, results in these systems being overloaded, with cross connections and ultimately increased pollution levels. This social and infrastructural reality influences the amount of pollution flowing into the coastal system through river and storm-water systems.
The Atlantic coasts water quality has shown a slight improvement over time. The slightly higher compliance levels than along False Bay are likely the result of not having the same geographical and climatic factors and a more formalised storm-water and sewage system. However, the improvements are still lower than required in order to ensure full adherence with the guidelines. This could be a result of factors of the natural and urban environments along this coastline. Contributing catchment areas are small and the bordering urban environment is densely populated, leaving little room for water-quality improvement before outlet into the sea.