Flood threat recedes as residents return to river towns

Heavy downpours and flooding have kept emergency services busy with evacuation orders and rescues. (HANDOUT/HUSKISSON VOLUNTEER RURAL FIRE BRIGADE)

Residents are returning to river towns near Sydney as the risk recedes of dangerous flooding from mass downpours.

Richmond Bridge over the Hawkesbury River has reopened but emergency services still warn motorists to drive carefully as buildings, roads and bridges might have damaged in the deluge.

People from Pitt Town Bottoms were given the okay to return home on Sunday morning with caution, hours after those from Camden and Ellis Lane were allowed back.

The Hawkesbury River remains swollen on Sunday, well above the minor flood warning level, and the NSW State Emergency Service warns that would persist into Monday.

Richmond Bridge is only open to vehicles less than 4.5 tonnes, and remains closed to pedestrians.

More than a dozen rescues were among hundreds of incidents amid floods and heavy rain, the SES says. (HANDOUT/NSW RURAL FIRE SERVICE)

Heavy rainfall soaked Sydney and other parts of the state last week, causing Warragamba Dam to spill for the third time in three months and threatening communities downstream in the Hawkesbury-Nepean Valley.

The SES said it responded to almost 300 incidents in the 24 hours to 8am on Saturday including 13 flood rescues, and issued 45 warnings across the state.

Swelling rivers brought moderate flooding to North Richmond that peaked on Saturday morning, the Bureau of Meteorology said.

At Windsor, the river peaked on Saturday and was down on Sunday afternoon, and is expected to fall below the minor flood level overnight into Monday.

Flooding at Sackville is subsiding and well below the minor flood level.

The danger is not entirely over, with residents in parts of Wisemans Ferry told they could be isolated without power, water or other essentials on Sunday.

Emergency services will begin to survey the damage to communities as waters recede, with possible impacts to infrastructure including roads.

Riverine and flash flooding may come without significant further rain, the SES chief warns. (HANDOUT/NSW RURAL FIRE SERVICE)

Warragamba dam outflows have slowed, but WaterNSW chief executive Andrew George said it may take a few days to return to normal.

The immediate threat of more damaging rainfall has eased, with the bureau not forecasting any further significant falls over the next few days.

"Our priority is to get people back to normal as soon as possible," NSW SES Acting Commissioner Deb Platz said.

But she warned residents to remain wary around the Hawkesbury Nepean catchment.

"We do not need to see significant rain to bring riverine and flash flooding," she said.

"As we have saturated catchments and full dams the rivers can rise very quickly."