Communities living downstream of major dams in the Western Cape are in no danger, despite several of these reservoirs being well over 100 percent full, the department of water affairs said on Friday.

Very heavy rains over the past few days in the Boland and Overberg regions of the province have flooded roads, washed away bridges, destroyed vineyards, submerged houses and raised fears about the structural integrity of several dams.

A farm dam on the Bok River in the Hex River area has already given way under the weight of water flowing into it.

Water affairs regional director Rashid Kahn told Sapa on Friday morning there was no cause for concern.

"We are monitoring the high in-flows constantly. The weather in the area has improved, and the worst is past."

He said the province's biggest dam, Theewaterskloof near Villiersdorp, where water is currently rushing over the spillways, was 106 percent full.

"These are major spillways, designed to take lots of run-off. The dam itself — which has a concrete wall — is designed to cope with much more than 100 percent.

"We don't need to open the sluice gates. This would cause a high rush of water. Allowing it to go down the spillways gives a more consistent flow downstream."

Kahn said the concrete wall of the Buffeljags dam near Swellendam was completely under water.

"We've had very high in-flows, but the river is subsiding and there's no danger at Buffeljags. It's an in-stream dam and designed to cope with this. We are monitoring it constantly."

On the Bok River dam, he said this was "already breached".

"This gave way about 24 hours ago. It is a private farm dam. It is not a big dam, and the danger has passed," he said.

The department was monitoring all dams in the region, including farm dams, and feeding the information through to disaster management authorities.

"There is no danger," Kahn said.

Sapa