WATER began cascading from Wellington Dam's wall early on Wednesday morning.
It is the second year in a row the dam has overflowed.
Last week the Water Corporation South West regional manager John Janssen warned people visiting to witness the spectacle to take care.
“Seeing water cascade over the 367 metre long crest of the concrete wall at Wellington Dam is a spectacular sight, with huge numbers of community members usually descending on the area,” Mr Janssen said.
“Even though the dam overflowed last year, we’re still expecting the same reaction this year. It is important the community remain in the designated areas for their own safety, especially in the wet conditions.”
Water Corporation strengthened the wall in 2009, by installing a series of high-tensile steel cables vertically through the wall and into the bedrock below.