The Integrated Vaal River System remains in a strong position despite slight declines in water levels at several major dams.

This is according to the Department of Water and Sanitation’s latest weekly state of reservoirs report.

The department said the system declined marginally from 99.2% last week to 98.9% but remains in an excellent state with sufficient water available to meet domestic, industrial and agricultural demand.

The Vaal Dam, the country’s second-largest dam and the main source of water for Gauteng and surrounding provinces, dropped from 103.4% to 102.4%.

Despite the slight decrease, the dam remains above full supply capacity. During the reporting period, inflows exceeded controlled outflows, indicating that water continued flowing into the reservoir while releases were managed to regulate storage levels and maintain downstream river flows.

The department said the minor decline was expected due to seasonal evaporation and the absence of rainfall and did not raise any concerns.

Grootdraai Dam also recorded a slight decrease, dropping from 98.9% to 98.6%, while Sterkfontein Dam remained unchanged at 99%.

Bloemhof Dam was the only major reservoir to record an increase, rising from 105.0% to 106.71%. The department said the increase reflected the continued movement of water through the lower Vaal River system from upstream reservoirs and helped maintain overall system stability.

Within the Lesotho Highlands Water Project, Katse Dam declined from 88.2% to 86.8% due to scheduled water transfers to South Africa while Mohale Dam dropped slightly from 101.9% to 101.8%.

The department said both reservoirs remained at healthy storage levels and continued to support water transfers into the Integrated Vaal River System.

“The healthy storage levels underscore the resilience of the catchment following a favourable rainfall season and provide assurance that the system is well-positioned to sustain water supply in the months ahead,” the department said.

It added that reservoir performance would continue to be closely monitored while water releases are managed to balance supply requirements, infrastructure safety and environmental flow obligations.

The department also reminded residents that although dam levels remain healthy, South Africa is a water-scarce country and water should continue to be used responsibly to help secure future supplies.