Two men were swimming at Oura Beach 15km north east of Wagga Wagga at about 6.45pm on Thursday, when they got swept down the river.

One man, in his mid 20's, managed to swim to shore, while the other man, 25, was swept away and has not been seen since.

The man alerted authorities and local police attended and started the search along with volunteer rescuers.

The search stopped on nightfall and began again from 6am on Friday with the assistance of police divers.

Anyone with information is urged to call Crime Stoppers on 1800 333 000 or at https://nsw.crimestoppers.com.au/

The man's disappearance came as ACT minister for sport and recreation Shane Rattenbury urged Canberrans to take care in the territory's waterways.

The warm weather and holidays are drawing people to the Murrumbidgee and swimming spots such as Uriarra Crossing, Casuarina Sands, Kambah Pool, Tharwa Sandwash, Pine Island and Cotter Bend.

Mr Rattenbury said swimmers should take note of safety signage, particularly relating to water depth and submerged objects, always supervise children and refrain from swimming after drinking alcohol.

"People should not be afraid of the water, but they should be aware of a few simple precautions they should take to stay safe," Mr Rattenbury said.

Similar safety awareness was important for those using backyard and public pools.

Information about the ACT's main natural swimming spots is available at tams.act.gov.au.