Queanbeyan's State Emergency Service volunteers spent much of Monday night preparing to hit the ground running ahead of the deluge.

Some minor flooding has already been recorded in Queanbeyan as of Tuesday morning, with the Morisset Street bridge closed due to the rising waters, along with the Oaks Estate Crossing.

SES crews have already briefed travellers staying at the nearby caravan park on the dangers of the rising floodwaters in the event an evacuation is ordered.

Meanwhile, several low-lying roads have been closed in the ACT, due to large amounts of water being released from Scrivener Dam, after Canberra's catchment dams reached 100 per cent on Monday.

Uriarra Crossing and Coppins Crossing has been closed to traffic due to flooding, with Point Hut Crossing also inaccessible to drivers.

An ACT Emergency Services Agency spokeswoman said Canberra SES crews responded to 23 requests for help since 6pm on Monday, with six jobs still outstanding.

Most of the jobs overnight were for leaking roofs and fallen trees.

The spokeswoman said the requests for help following the heavy rain were evenly scattered across the city, with the damage not limited to a particular area of Canberra.

SES Queanbeyan unit Operations officer Brent Hunter said crews were ready to tackle the damage left by the rain ahead, and the unit was keeping as many crew members close to home as possible, in case the weather turned for the worse.

"There's been an obvious rise in the river heights around Queanbeyan and we have seen a few road closures," he said.

"However, we're still not expecting an inundation of properties, but is a dynamic situation.

"The biggest area of concern for us on Tuesday is the Queanbeyan CBD."

Across NSW, tens of thousands of people have been evacuated as rivers rise, highways are shut and homes washed away.

A Queanbeyan team was sent north to Picton to assist with flood rescues.

The Bureau of Meteorology issued a minor flood watch for the Queanbeyan and Molonglo rivers on Monday afternoon.

With Googong Dam at capacity and days of consistent rain, the Queanbeyan River had already started to swell.

The four dams in the region are at 99.96 per cent. They have been nearing capacity since November, a remarkable turnaround from January 2020, when stores dropped to less than 45 per cent.

Mr Hunter said rivers would continue to rise throughout Tuesday but there was no immediate risk to life or property.

He said residents should stay alert and prepare their properties.

"It's all those regular maintenance things like cleaning out your gutters and, [residents should] continue to monitor the situation for the next 24 to 48 hours," he said.

Holly Mansell and her family have been living at the bank of the Queanbeyan River for close to a decade.

The water has encroached up to her back fence before, about 20 metres from where the water's edge usually lies.

Holly said her family were prepared but not concerned about Tuesday's downpour.

The riverside home has been subject to many minor flood watches. The house has been prepared, items have been moved to a safe home.

The family, like all waterside residents, will be watching closely as the weather unfolds.

A Queanbeyan-Palerang Regional Council spokesman said rural areas with many low-lying causeways were of the biggest concern.

Roads at Braidwood and Bungendore were closed on Monday including Resches, Back and Jembaicumbene creeks.

The ACT Emergency Services Agency warned other low-level roads would close on Tuesday as the rain hit.

The council spokesman said workers would be out on Monday and Tuesday putting in place a "Band-Aid" fix where possible, but warned consistent rain would continue to cause problems.

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Mr Hunter stressed people should stay away from flood waters and no one should ever drive through fast moving water.

"Last time [it flooded], the roads washed away and drivers didn't realise until they were driving through them," he said.

"That puts their lives at risk, and the lives of our volunteers."

The Bureau recorded 51mm of rain in Tuggeranong since 9am on Monday and 27mm at Canberra Airport s

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