The state of freshwater quality in Cape Town has seen a slight improvement from previous years. However, it still falls short of targets set in 2014. The inability for the majority of the rivers and a few of the wetlands and vleis to reach the IMEP 80% target and continuing high trophic levels is a result of a number of contributing factors. Trying to identify the exact reasons for improvements in freshwater quality is incredibly complex, as the City’s attention and action to freshwater management has increased over time.
Contamination of the city’s freshwater systems is primarily due to contaminated urban storm water and raw sewage from informal settlements, leaking sewers and pump stations. The continuously increasing rate of urbanisation, rapid expansion of informal areas and an increase in backyard dwellings further strains the City’s capacity to service and build new infrastructure.
See the Wastewater Chapter for information on the general standards used to control phosphorous concentrations
There are no strict national standards for phosphorous concentrations in treated wastewater effluent that apply to City of Cape Town waste water treatment works (WWTW). However, the City makes use of general standards for phosphorous and has committed to new efforts in ensuring that WWTWs are able to remove phosphates effectively. This is currently being operationalised at the Wildevoelvlei WWTW.
It is important to note that bacterial pollution and nutrient enrichment do not always correlate. Some systems that have poor trophic tendencies may have good levels of compliance with bacterial guidelines, such as Wildevoelvlei. This is a result of effective disinfection of effluent discharged into the vlei from the adjacent Wildevoelvlei WWTW but a poor reduction in effluent phosphate levels. However, in the absence of man-made influence, wetlands and vleis will naturally accumulate more organic nitrogen and phosphorus, resulting in continuous nutrient enrichment, than rivers. Therefore, it is not possible to have all water bodies classified as oligotrophic and being able to meet both ecosystem and public-health guidelines. It is necessary, however, to ensure that the water systems do not change permanently into a higher trophic state.
In line with its intention to become a ‘water sensitive city’ and the framework of the Inland and Coastal Water Quality Improvement Strategy, the City has a number of ongoing projects in place to improve water quality. These include an increase in maintenance for clearing litter and dumped material from storm water systems, improving aquatic weed and algae management measures, improving informal settlement servicing and managing databases to include downstream water-quality criteria, and eliminating sewer-to-storm-water cross connections, to name a few.
Furthermore, the City has partnered with a number of entities, including other spheres of government, neighbouring municipalities, business, agriculture, community groups and non-governmental organisations, to ensure the improvement of freshwater quality. The City has also partnered with national government and the Western Cape Provincial Government to supplement City enforcement agencies in order to manage water pollution. The City has also implemented the national ‘Adopt-a-River Programme’ to encourage communities to adopt and clean dirty rivers. The City also participates in initiatives such as the Western Cape Wetlands Forum with the aim of fostering wetland protection and promoting related research.
IDP: Strategic Focus Area 3 – The Caring City
Inland and Coastal Water Quality Improvement Strategy
Storm Water Management By-law
SDG 6: Ensure access to water and sanitation for all