Integrated Vaal River System remains stable with healthy storage levels
The Department of Water and Sanitation’s (DWS) latest weekly State of Reservoirs report indicates that the Integrated Vaal River System (IVRS) continues to maintain strong and stable storage levels despite moderate declines recorded at some major dams within the system. Most reservoirs remain at exceptionally healthy levels, with several dams still operating above full supply capacity, reflecting sustained water security across Gauteng and surrounding provinces.
The Vaal Dam declined slightly from 111.0% to 109.0% but continues to remain significantly above full capacity. The decrease indicates that operational releases and downstream outflows exceeded inflows during the reporting period as part of ongoing dam safety and water level management measures following prolonged overcapacity conditions. Despite the marginal decline, the dam continues to hold substantial volumes of water, reinforcing its critical role in supporting domestic, industrial, mining, and agricultural water supply across Gauteng and neighbouring provinces. Storage levels above 100% continue to reflect a strong hydrological position and sustained catchment recovery.
The Grootdraai Dam recorded a slight increase from 102.6% to 102.9%, demonstrating continued inflows within its catchment area. Remaining above full supply capacity confirms hydrological stability and continued positive contribution to the broader Vaal River System.
The Sterkfontein Dam, which primarily functions as a strategic reserve reservoir, recorded a marginal decline from 99.6% to 99.5%. This minimal movement reflects stable reserve conditions and limited drawdown from storage. The dam remains a critical component of long-term water security, particularly during periods of reduced rainfall and elevated demand pressures.
Bloemhof Dam also recorded a moderate decrease from 108.4% to 105.4%, although it remains substantially above full capacity. The reduction reflects continued high-volume releases aimed at regulating storage levels and managing downstream river conditions following sustained periods of elevated inflows. Despite the decline, the dam remains in a strong hydrological state, with storage levels above 100% indicating continued water abundance within the system. The reservoir continues to be actively managed to balance storage stability, infrastructure safety, and flood mitigation requirements.
Overall, the Integrated Vaal River System (IVRS) declined slightly from 103.9% to 102.1%, remaining comfortably above full capacity. The IVRS comprises a complex network of interconnected dams and transfer schemes, including the Vaal, Grootdraai, Sterkfontein, Bloemhof, Katse, and Mohale dams, which collectively support water supply to Gauteng and key economic sectors across the country.
A system storage level above 100% reflects exceptionally strong water availability across the network, ensuring sufficient supply to meet domestic, industrial, mining, and agricultural demands. The slight decrease to 102.1% suggests that operational releases and downstream outflows are gradually exceeding inflows as dam managers continue implementing measures to stabilise reservoir levels after extended periods of high storage conditions. Importantly, the current storage levels confirm that the system remains balanced, resilient, and capable of providing continued short-term water security while supporting safe infrastructure management and downstream river flow requirements.
Within the Lesotho Highlands Water Project system, the Katse Dam recorded a decline from 98.6% to 95.5%. The decrease reflects continued water transfers and operational releases associated with the transfer scheme. Despite the more noticeable reduction, the reservoir remains at a strong storage level capable of sustaining ongoing transfers into South Africa. The dam continues operating efficiently within a managed supply framework balancing inflows, transfers, and long-term storage sustainability.
Similarly, the Mohale Dam decreased from 103.8% to 102.5%, while remaining above full supply capacity. The decline reflects controlled operational releases within the Lesotho Highlands transfer system while maintaining robust storage conditions. The continued status above 100% confirms sustained hydrological strength and the dam’s ongoing contribution towards augmenting water supply into the Integrated Vaal River System.
The Department of Water and Sanitation will continue closely monitoring all reservoirs and implementing necessary operational measures to ensure safe infrastructure management, sustainable water supply, and effective flood risk mitigation across the Gauteng region and broader Integrated Vaal River System.
Despite the current healthy storage levels, the Department continues to encourage all consumers to use water wisely and responsibly to ensure long-term water security for future generations.
For more information, contact:
Wisane Mavasa
Spokesperson for the Department of Water and Sanitation
Cell: 060 561 8935
E-mail: mavasaw@dws.gov.za
Maria Lebese
Gauteng DWS: Communication
Cell: 082 611 9264
E-mail: lebesem@dws.gov.za
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