Integrated Vaal River System remains well supplied despite marginal decline in dam storage levels
The Department of Water and Sanitation (DWS) reports that the Integrated Vaal River System (IVRS) recorded a marginal decline in its overall storage levels, decreasing from 97.8% last week to 97.4% this week. Despite the slight decrease, the system remains relatively well supplied and close to its combined full supply level (FSL). The latest assessment reflects varying storage levels across individual reservoirs, with most dams recording marginal weekly declines.
Vaal Dam recorded a decrease from 105.1% last week to 104.3% this week. Despite the decline, the dam remains above its 100% FSL, indicating that its recorded storage is still above its defined full supply reference level. Although the reservoir experienced a slight reduction in storage during the reporting period, it continues to maintain levels above its FSL.
Grootdraai Dam recorded a marginal decline from 99.2% to 99.0%, remaining slightly below its FSL. The relatively small change indicates that the reservoir's storage levels have remained stable over the past week. However, continued monitoring of rainfall, river inflows, water releases and consumption remains important in tracking changes in its storage position.
Bloemhof Dam declined from 93.1% last week to 92.2% this week. The reservoir remains below its FSL, with the latest reading reflecting a further reduction in its stored water. Its storage levels are influenced by various factors, including rainfall and runoff within the catchment, upstream river flows and operational water releases.
Sterkfontein Dam maintained a stable storage level of 98.8% for the second consecutive week. The unchanged reading indicates no recorded variation in its storage percentage during the reporting period. Although the reservoir remains slightly below its FSL, its consistent storage position reflects relative stability over the past two weeks.
Mohale Dam, in contrast, recorded a slight increase from 102.0% last week to 102.1% this week, remaining above its FSL. The marginal improvement reflects a small increase in its reported storage level. As part of the interconnected water supply infrastructure, the reservoir contributes to the broader management and availability of water resources within the system.
Katse Dam recorded a marginal decline from 85.7% to 85.1%, remaining below its FSL. The latest figures indicate a slight reduction in the reservoir's stored water compared with the previous week. Its storage levels are influenced by rainfall and runoff within its catchment, river inflows, water transfers and operational requirements.
The overall IVRS storage level decreased from 97.8% last week to 97.4% this week. The system comprises an interconnected network of dams, reservoirs and water infrastructure that supplies Gauteng and other areas, supporting domestic, industrial, agricultural and broader socio-economic water requirements. It is important to note that the overall IVRS percentage represents the combined storage status of the interconnected system and not the storage level of any individual dam. Consequently, individual reservoirs may record different storage percentages while contributing to the overall system capacity.
Dam storage levels are influenced by several factors, including rainfall, catchment conditions, river inflows, surface runoff, water transfers, controlled releases, evaporation and consumption. Rainfall within a catchment does not necessarily translate into an immediate increase in dam levels, as the volume of water reaching reservoirs depends on the location and intensity of rainfall, runoff patterns and prevailing catchment conditions. Water demand and operational releases also contribute to fluctuations in reservoir storage.
The Department urges communities, businesses, industries and all other water users to continue practising responsible water use and to avoid unnecessary wastage. While the IVRS remains relatively well supplied and close to its combined FSL, the marginal decline recorded this week highlights the importance of sustained water conservation efforts, efficient water resource management and continuous monitoring to ensure the long-term sustainability and security of the country's water resources.
Media Enquiries:
Wisane Mavasa
Spokesperson for the Department of Water and Sanitation
Cell: 060 561 8935
Email: mavasaw@dws.gov.za
Maria Lebese
Gauteng DWS: Communication
Cell: 082 611 9264
Email: lebesem@dws.gov.za
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