Victoria is installing a permit system for South Australians to enter the state as it's "hard border" with its neighbour is set to loosen.
From 11.59pm Saturday, SA residents will require a permit to enter Victoria unless an exemption applies, a Victorian government spokeswoman on Saturday evening said.
The new rule does not apply to cross-border communities who have until recently been affected by SA's coronavirus border restrictions on Victoria.
"People who live in the previously established 70km cross-border bubble between Victoria and South Australia will not require a new permit, but they will be required to use existing permits from the South Australian government," the spokeswoman said.
"Those receiving or providing emergency medical care, providing or receiving emergency services or residing on a property that extends across both South Australia and Victoria will be exempt from the requirement for a permit."
People who have visited an SA location deemed "high risk" will not be allowed to visit Victoria unless they have an exemption.
Victoria Police will monitor permits through spot checks and health department officials will meet flights at airports.
Permits are available from the Service Victoria website.
The Victorian move is in response to an Adelaide cluster numbering 26 cases and after viral fragments were found in waste water testing sites at Benalla and Portland.
Victoria has gone 22 days with virus transmission and has just one active case left.
The single case is an immunosuppressed person making a "slow and steady" recovery, Health Minister Martin Foley has said.
Authorities are concerned about traces of the virus unexpectedly found at a Melbourne waste water facility, prompting a plea for residents and visitors to Altona in Melbourne's southwest from last Monday to Wednesday to get tested if symptomatic.
The result is unexpected because it has been about eight weeks since someone in the area tested positive.
Suburbs in the catchment include Altona, Altona Meadows, Laverton, Point Cook and Sanctuary Lakes.
The state is preparing for the reinstatement of hotel quarantine, which sparked the second wave, when international arrivals resume on December 7.
Initially, the traveller cap will be 160 per day.
Australian Associated Press