West Australian Premier Mark McGowan has likened the state's hard border closure to Brexit, warning it could be months before the travel ban is lifted, as 17 new cases of COVID-19 were confirmed.
WA has recorded a total of 453 coronavirus cases, including 18 people currently in intensive care.
A further 159 people were arriving at Perth Airport on Sunday and would be quarantined.
WA will enforce its unprecedented temporary hard border closure from 11.59pm on Sunday.
"Brexit has taken four years and we put borders in place in the space of one week," Mr McGowan told reporters on Sunday.
The premier acknowledged it would cause frustration for many people and turn lives upside down.
"But we're in a state of emergency. The situation we find ourselves in is not of our making," he said.
"We need to use our isolation to our advantage. The alarm bells have been ringing for some time.
"We have issued warning after warning to West Australians who are over east. By now they should be home."
There will be exemptions for health workers, emergency services, freight workers, people providing specialist skills, judicial services and on compassionate grounds.
FIFO workers and their families will also be exempt but must adhere to a 14-day isolation period upon entering WA.
Also, those who return after spending 14 days in hotel quarantine in other states will have to isolate for a further fortnight.
Mr McGowan said people should be prepared for about six months of restrictions.
"It's going to be a long, hard winter of restrictions and that is a very unfortunate reality," he said.
"I know it might seem like COVID-19 has been going on for a long period of time now, but unfortunately we've only just started our battle here."
WA is also enforcing intrastate travel restrictions, especially to remote Aboriginal communities.
In the Kimberley region, where more than a dozen cases have been confirmed, travel between the four local government areas is also forbidden.
In the Goldfields-Esperance region, local people are now banned from visiting coastal holiday hotspot Esperance except for essential services.
Among the rejected excuses people have come up with at various checkpoints were a man who said he needed to buy chooks to produce eggs, a bus with 10 tourists on a day trip, and people wanting to go fishing or chop firewood.
Mr McGowan said the coronavirus-plagued Artania cruise ship remained docked in Fremantle but five decks had been cleaned.
Meanwhile, Consumer Protection commissioner Penny Lipscombe said she was concerned some tenants were failing to pay rent despite not genuinely experiencing severe financial hardship.
"It is reasonable for a landlord to ask for proof of termination of employment or other evidence of financial distress, but should not ask to look at copies of bank statements," she said.
Australian Associated Press