Woronora Dam is close to 90 per cent full after all the rain - but people who are keen to take a look will have to wait till next week.
On Friday, the dam was at 89.8 per cent capacity, a rise of 18 per cent in the last week.
A Water NSW spokesman said the last time Woronora Dam was at a comparable level was at the beginning of 2017/18.
"However it should be noted that it was falling from its peak towards the end of 2017," he said.
The spokesman said the dam had been closed to visitors this week, and would remain so on the weekend.
It will reopen on Tuesday.
Some other Sydney dams are open on the weekend.
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