Police confirmed the body of a man, aged 75, had been recovered from the water after a significant search effort.

The man had been reported missing about 12.30pm and had been at the swimming spot with family. Police announced the man's death at 4pm on Saturday.

Acting Sergeant Angus Fergusson from the Tuggeranong Police Station said circumstances of the man's death were under active investigation.

The man had initially been assisted by a kayaker, who had been unable to pull him from the water, he said.

The search effort had been supported by ACT Ambulance, ACT State Emergency Service and Australian Federal Police officers.

Earlier on Saturday afternoon, a Toll ambulance rescue helicopter was flying low over the river in the afternoon, while officers from search and rescue officers and the Australian Federal Police's maritime specialist response group were deployed.

The helicopter was hovering about 100 metres above the river, making slow passes from the main rock pool to an area about 300 metres downstream.

The doors to both sides of the helicopter were open, with officers stationed on either side of the aircraft to spot for signs of the missing man below.

The steep sides of the Murrumbidgee mean there is no safe place to land.

There were police officers on either side of the river scouring the banks.

The Murrumbidgee River was high and running strongly following recent rain, with murky brown water.

Acting Sergeant Fergusson said while the weather in Canberra had improved in recent days, the waterways were still quite cold.

"We would like to take this opportunity to remind Canberrans who are making use of the natural waterways and water features in Canberra to take extreme care when they're swimming," he said.

"People should always exercise caution at anytime of the year when they're making use of the natural waterways in the ACT. Certainly after heavy rain, they should consider whether it's safe to enter the waterway. And if they're unsure, they shouldn't enter."

Kambah Pool had been closed for swimming following a bacteria alert in the Murrumbidgee River, but remained open for boating and secondary contact activities.

More than 54 people have died in waterways across Australia since the start of December, up from 48 drowning deaths in the same period last year.

The toll reveals men aged 18 to 34 are most at risk, while more people drown in inland waterways like rivers, lakes and dams than at the beach.

Four people drowned in ACT waterways in 2020-21.

More to come.

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