Premier Mark McGowan on Monday said WA had 213 new local cases and 11 travel-related infections.
He warned more cases were likely in the community of Jameson, about 1000km east of Kalgoorlie.
Mr McGowan said the two people who had tested positive there had travelled into WA from South Australia via back roads, breaching the state's border rules.
"They've been fined as a consequence," Mr McGowan told reporters.
"Police have locked down that community. The people who were positive are in quarantine and police are monitoring the situation.
"We expect there will be other people infected and we'll do what we can to manage that situation in the community."
WA Health on Sunday said there were about 50 people in the community, and five close contacts linked to the cases were also isolating.
The department said it was working with Ngaanyatjarra Health Service to manage the outbreak.
There are around 230 remote Aboriginal communities in WA, with low vaccination rates a concern in those parts of the state.
"The fact the virus is in one community will hopefully spur more people to get vaccinated," Mr McGowan said.
WA's active case tally has grown to more than 1000 as the state prepares to reopen its borders to vaccinated travellers from March 3.
New public health measures are now in effect in Perth and five other regions, including a density rule at hospitality venues of one person per two square metres.
Home gatherings are now capped at 30 people and private outdoor events in non-home settings capped at 200 people.
Visitor limits have also come into effect at hospitals and aged care facilities.
Mr McGowan defended the "relatively modest" restrictions which have faced some criticism from the hospitality sector.
He said strict proof of vaccination rules would remain in place at most venues until there was improvement in the third-dose rate.
About 57 per cent of eligible West Australians have so far had their booster.
"The only way we got to high levels of vaccination was via the mandates," Mr McGowan said, noting that WA had previously avoided widespread community transmission.
"Had we not done that, we wouldn't have gotten there ... then we'd have people getting very sick, many dying and our hospitals being overwhelmed."
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