Sydney’s Warragamba Dam has started to overflow after days of heavy rain in the region, which is expected to continue for a number of days, the Sydney Catchment Authority said.
Authorities have warned western Sydney residents to be ready for minor flooding, while southern residents are still waiting to get back to their flood-affected homes following the severe weather.
The spillover is expected to be less than it was predicted in previous forecasts, but the water level's in the dam will be lowered to just below full supply as part of the post-flood procedures.
Also, emergency crews warned locals that some roads and bridges may be closed.
Avon Dam, Nepean Dam and Tallowa Dam are also spilling.
Warragamba, Sydney’s major dam, is spilling for the first time since 2013. It is located about 70 kilometre west of Sydney and is the largest urban water storage in Australia, it provides about 80 percent of the Sydney region's drinking water.
The State Emergency Service (SES) has worked to attend more than 1,700 calls for help, since the wild weather hit the Sydney region on Monday.