Strong reservoir levels bolster water security across the Integrated Vaal River System
The Department of Water and Sanitation (DWS) reports that the Integrated Vaal River System (IVRS) remains in a stable and healthy position, with storage levels across the major reservoirs continuing to provide a strong water-supply buffer. Although the latest weekly assessment reflects a marginal decline in overall system storage, several key dams remain at or above full supply capacity, underscoring the system’s favourable storage position and resilience.
The Vaal Dam, one of the principal reservoirs supplying Gauteng and a critical component of the IVRS, is currently at 101.0%, compared to 101.3% last week, representing a marginal decline of 0.3 percentage points. The dam remains above full supply capacity, providing a substantial storage buffer for the Gauteng water-supply system. During the reporting period, Vaal Dam received 46.4 mm of rainfall, recorded an inflow of 42.43 m³/s and a discharge of 16.765 m³/s. The inflow remained higher than the discharge, indicating continued replenishment of the reservoir from the catchment.
The Grootdraai Dam is currently at 96.9%, down slightly from 97.1% last week. Despite the marginal decrease, the dam remains close to full supply capacity and continues to reflect healthy storage conditions. Week-on-week fluctuations are influenced by inflows, releases and water demand and, in this instance, do not raise any immediate concern regarding the reservoir’s storage position.
The Sterkfontein Dam remains unchanged at 98.8%, maintaining its near-full storage position. The stability of the dam reflects a relatively balanced relationship between inflows, releases and water losses. Its high storage level continues to strengthen the strategic reserve available within the IVRS.
The Bloemhof Dam is currently at 106.32%, compared to 106.4% last week, representing a marginal decline of 0.08 percentage points. The dam remains substantially above full supply capacity. During the reporting period, Bloemhof Dam recorded a gauge plate reading of 18.320 metres, a discharge of 40.471 m³/s, rainfall of 10.6 mm and evaporation of 0.4 mm. The high storage level and controlled releases form part of the ongoing operational management of the lower Vaal River system, supporting appropriate reservoir levels and downstream flows.
In the Lesotho Highlands Water Project (LHWP), Katse Dam declined from 84.5% last week to 83.4% this week. While its storage level is lower than that of several other reservoirs in the IVRS, Katse continues to hold a substantial volume of water. Its storage fluctuations must be viewed within the context of the operational releases and transfers undertaken through the LHWP to augment water supplies to the Vaal River System.
Mohale Dam remains unchanged at 101.7%, the same level recorded last week. Remaining above full supply capacity, the dam continues to provide strong storage support. Together with Katse Dam, Mohale forms part of the LHWP and contributes to the augmentation of water supplies to the IVRS.
Overall, the Integrated Vaal River System declined marginally from 98.8% last week to 97.9% this week. Despite this decrease, the system remains very well supplied, with substantial volumes of water stored across its major reservoirs. The weekly movement is consistent with the normal and continuous operation of an interconnected water-supply system, where water is transferred and released to meet demand, maintain river flows and manage reservoir levels.
Changes in system storage are influenced by a combination of factors, including rainfall, catchment inflows, operational releases, transfers, evaporation and water consumption. The fact that several strategic reservoirs remain at or above full supply capacity provides an important buffer and contributes to continued water-supply assurance for Gauteng and other areas served by the IVRS.
The Department will continue to monitor the IVRS closely and manage the system in a coordinated and sustainable manner to balance water availability, demand, transfers and reservoir levels, particularly as hydrological conditions change.
Notwithstanding the favourable storage position, DWS reiterates that South Africa remains a water-scarce country. High dam levels should therefore not lead to complacency. All water users, including households, municipalities, industries, businesses and the agricultural sector, are urged to continue using water responsibly and efficiently.
The Department further calls on communities to protect water resources and infrastructure, prevent water wastage and support efforts to ensure that available water is conserved for current and future generations.
For more information, contact Wisane Mavasa, Spokesperson for the Department of Water and Sanitation on 060 561 8935/ mavasaw@dws.gov.za or Maria Lebese (Gauteng DWS: Communication on 082 611 9264 / lebesem@dws.gov.za
For media releases, speeches and news , visit the Water and Sanitation portal at: www.dws.gov.za
#GovZAUpdates
