The system is critical for water supply in major economic sectors in Gauteng, North West and Mpumalanga.
Water and Sanitation spokesperson Sputnik Ratau said Eskom and Sasol petro-chemical plants rely on the system.
Eskom gets water for its coal-fired power stations from the Vaal River Eastern Sub-System (VRESS) which supplies water to 11 Eskom power stations and is part of IVRS.
“Slightly moving down this week, the IVRS declined from 66.3% last week to 65.5% this week. The present levels of the dam are lower compared to the same week last year when the system was at 81.4%,” Ratau said.
The Vaal dam is a major contributor to the dropping levels. Ratau said that dam levels fell from 59.3% last week to 58% this week.
“This shows a huge difference in the levels of the dam between now and last year at the same time when it stood firmly at a strong 91.9%,” he said.
Ratau said the department is calling on Gauteng residents to be mindful of the depleting dam levels and urged them and adapt their water use accordingly.
“Similarly recording a decline this week, the Grootdraai Dam slightly declined to 60.0% from last week’s 61.2%. In the preceding year at the same time the dam stood at 84.3%,” said Ratau.
The dam in Standerton provides water needed for the Sasol II and III petroleum from the coal plant in Secunda.
Bloemhof Dam also sank when levels dropped from 96.5% to about 95% this week.
Last year during the same period the dam stood at 98.1%.
“This week the Mohale and the Sterkfontein dams remained stagnant as they held to last week’s levels. The Mohale Dam is presently at 33% while the Sterkfontein hovers at 92%. However, what differentiates the two dams is that during the comparative period last year, the Mohale Dam floated at a trivial 23.1% and the Sterkfontein Dam was on the upsurge at 98.1%,” said Ratau.
He urged water users to do their part in saving water as this would have a great impact on the declining water levels.