RAND WATER ANNUAL REPORT 2023

HOW WE CREATE VALUE

Vaal Dam Catchment Area At the start of the reporting period (1 July 2022), the Vaal Dam’s level was at 105%. On 24 July 2023, the level was 92%, much lower than the corresponding time the previous year.

22km

Mohale Dam TSC: 0.84 billion m 3 Lesotho 2023: 101.7% 2022: 98%

Katse Dam TSC: 1.95 billion m 3 Lesotho 2023: 94.6% 2022: 94%

Woodstock Dam

29km 2

38km 2

TSC: 0.38 billion m 3 Kwa-Zulu-Natal 2023: 99.8% 2022: 101%

40%

Sterkfontein Dam TSC: 2.62 billion m 3 Free State 2023: 100.7% 2022: 100%

67km 2

145m

180m

Pumped Transfer

Gravity Fed Transfer

93%

Nuwejaarspruit

Pumped Transfer

TSC: 0.35 billion m3 Mpumalanga 2023: 94.5% 2022: 100% Grootdraai Dam

39km 2

Liebenbergsvlei

Wilge

27m

321km 2

Vaal

Vaal Dam TSC: 2.57 billion m 3 Gauteng 2023: 92.0% 2022: 105%

23m

Vaal

233km 2

Bloemhof Dam TSC: 1.26 billion m3 Free State, North-West 2023: 101.8% 2022: 104%

Dam Status & Total Storage Capacity (TSC)

Increase over the previous year - Decrease over the previous year

Figures 22: Vaal Dam Catchment Area Dam Level Status of the Upper Vaal River System

Several water quality issues were identified regarding the current water quality assessment of the Vaal River system. Some issues impact the full length of the Vaal River while others are local in nature. Vaal Dam was over 100% for the greater part of 2022/23 with high inflows and outflows. Due to the inundation of the dam riparian areas and decomposition of vegetation, the colour issue persisted. However, the water quality was extensively analysed during this period and found not to be harmful for human consumption. The occurrence of microbiological pollutants as localised problems is also a continuous concern. Eutrophication is the other key water quality challenge in the Vaal River System as it causes algal blooms. These blooms are occurring more frequently and with increased severity than what was historically experienced. Municipal wastewater effluent is the principal contributor to eutrophication and degradation of the Vaal River aquatic system. Several directives have been issued by DWS to some of the municipalities in the catchment, instructing them to improve the quality of their effluent discharge from wastewater treatment works. Unfortunately, this has not had the desired effect. In the long-term, population expansion and development in the Vaal River catchment are expected to increase pollution levels. Additional measures and strategies to maintain acceptable pollution levels in the Vaal River system will be required.

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