Tens of thousands of head of cattle are likely to have been lost in the state's worst flooding, according to the Kimberley Pilbara Cattlemen's Association.
"Certainly an unprecedented event that has taken a lot of management and a lot of energy," association chair Jak Andrews told reporters on Thursday.
"Its quite difficult and it's really emotive. Pastoralists are really passionate about their livestock."
Mr Andrews said the full extent of the cattle losses wouldn't be known until the water receded.
He added it would be very costly to rebuild the region's herd, roads and infrastructure and significant government support would be needed.
WA Agriculture Minister Jackie Jarvis said the flood had also impacted the region's only abattoir, Kimberley Meat Company.
There are concerns the business might have to stand down its 100 workers after the flood wiped out thousands of head of cattle ready to be slaughtered.
Ms Jarvis said it was unlikely to impact the state's meat supplies or beef prices but support would be provided to help the exporter stay open.
An emergency animal welfare order has also been issued to enable livestock in flooded areas to be culled if they are without access to feed and fresh water.
The Bureau of Meteorology says flooding in the Fitzroy River catchment has eased and the widespread heavy rainfall that inundated the region for more than a week has stopped.
The Great Northern Highway remains closed for about 700km between Broome and Halls Creek and partially open to high-clearance vehicles in other areas.
Emergency Services Minister Stephen Dawson said a 10km section of the major transport route had been completely washed away or badly damaged near Willare and it would take four weeks to build a temporary track.
"Along with Fitzroy Crossing this area sustained the brunt of the flooding," he said.
Work is also progressing on a temporary river crossing at Fitzroy Crossing, where a large section of a bridge on the only sealed road to the north of the state was washed away.
However, authorities have warned it may be many months before heavy road trains carrying freight can use the route.
Meanwhile, authorities continue airlifting essential supplies to cut-off communities, including 60 pallets of food transported to Derby on Thursday by the Australian Defence Force.
About nine tonnes of food have also been flown into Fitzroy Crossing since the emergency started and a barge carrying 110 tonnes of supplies has arrived in Broome.
Dozens of evacuated people have started returning to their remote communities from evacuation centres in Broome and Derby, where more than 100 remain waiting to go home.
Damage assessment teams have also started fanning out across the region but Mr Dawson warned it could be many months before repair work in towns like sodden Fitzroy Crossing was completed.
"We're using aircraft helicopters to transport people around, but there are some communities where there is still water," he said.
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