A video appears to show the Theewaterskloof Dam outside Franschhoek overflowing, which has caused people to believe the dam is spilling.
"This is a present position over the last few weeks, where wind action over the vast dam surface causes waves that occasionally spill over the spillway wall, making people believe that the dam [is] spilling," the Western Cape's Department of Water and Sanitation's (DWS) John Roberts told News24 on Saturday.
The dam, which was last full and overflowing in 2014, is the main domestic and industrial supply in Cape Town and Stellenbosch, Roberts added.
The Western Cape DWS, however, could not confirm the video's authenticity.
"The department currently cannot make an informed state of full supply as a result of the wave actions. The dam should, however, be near full," Roberts concluded.