The cost of raising the wall of Clanwilliam Dam in the Western Cape has increased.

“The raising of the Clanwilliam Dam will commence in October, at an estimated cost of R2.5 billion,” Water and Sanitation Minister Nomvula Mokonyane told MPs yesterday, opening the debate in Parliament on her department’s budget.

In the 2014 Estimates of National Expenditure tabled in February by then finance minister Pravin Gordhan, the dam’s estimated budget was R2.2 billion, 22 percent higher than the previous R1.8bn.

The estimates document attributes the rise to “cost adjustments made due to the delays in finalising the design and changes in the scope of work”. The latest increase means costs have risen R300 million in the past five months.

The Department of Water Affairs was not immediately available to comment.

Mokonyane said that the raising of the wall “will also include dam safety measures to ensure the stability of the embankment”. The wall’s safety has been a concern for years, in what the estimates document described as “distortion” in the structure. It was understood the wall would be raised by 13m, providing an additional 70 million cubic metres of water a year to downstream farmers.

Work started last year on re-aligning the N7 national road, parts of which would be flooded by water rising in the reservoir.