ALMOST half of the State's 160 dairy farmers tipped up to 1.5 million litres of milk worth more than $750,000 in income down the drain during the massive and fatal Waroona bushfire.

A further 100,000L of stale milk stored at the Harvey Fresh plant near Harvey township was dumped at a registered refuse disposal site at Mandurah on Tuesday after Forrest Highway reopened.

The Harvey Fresh plant and the nearby Harvey Beef abattoir were shut down for four days with staff evacuated for safety as the bushfire burned to within a couple of kilometres of the town.

Staff returned to both plants on Monday  the Harvey Fresh engineers started at 2am  to clean out burnt leaves and wind-blown ash and begin recovery mode operations.

Harvey Fresh general manager Paul Lorimer said supplies of the full range of Harvey Fresh milk and dairy products were not expected to fill supermarket shelves until next week.

"We did manage some production Monday and we are into full recovery mode today," Mr Lorimer said on Tuesday.

"We are concentrating on our staff and their welfare and trying to contact every one of them to make sure they are alright, ascertain what support they might need and when they want to return to work, and on trying to refill the supply pipeline."

He confirmed three Harvey Fresh staff had lost homes when Yarloop was destroyed on Thursday night and properties in the surrounding area owned by other staff or their relatives had sustained fire damage.

Harvey Fresh human resources manager Bob Lowther began working with staff on Friday morning to help find accommodation and other support for them.

The impact the four-day production shutdown will have on Harvey Fresh's dairy exports was as yet unknown, Mr Lorimer said.

He said export market packaging and dispatch had been one of the challenges last week.

"We normally do that towards the end of the week,'' he said.

"We will be in a better position this week to handle it.

"The majority of our customers, both domestic and export, have been very understanding and supportive, asking after our staff and how they are coping."

Harvey Fresh is the State's largest exporter of milk and dairy products.

Mr Lorimer confirmed all of Harvey Fresh's 67 raw milk suppliers were affected by the forced shutdown and had to dump milk because there was not sufficient refrigerated on-farm storage to keep it until pick-ups resumed.

He was involved in negotiations on Sunday with the inter-agency incident control team to attempt to get access for milk tankers into the bushfire emergency zone after the fire had passed.

"The tankers went out Monday and collected 390,000L, but because the (farm) vats were all fuller than normal, they couldn't get to everyone on Monday," he said.

"They were out again on Tuesday morning and everyone was picked up."

He confirmed Harvey Fresh had stipulated milk would only be collected if it was less than 48 hours fresh and stored at 4?C degrees or below.

Mr Lorimer said it was planned to start discussions later this week with farmers to work on some form of compensation package for the milk they had to tip into effluent dams or onto paddocks.

He said it was likely to be some time before the full cost of the fire to the company could be tallied.

Harvey Fresh farm liaison manager Ken Sharpe said three dairy farms supplying the company had sustained fire damage.

"They lost mainly pasture and fences and some will have lost some fodder and silage," Mr Sharpe said.

"At this time of the year we are normally looking for extra milk so that (farmers having to dump milk) is part of the tragedy."

At least five dairy farms in the Waroona, Yarloop and Harvey area that supply Brownes Dairy and Lion Dairy and Drinks were also affected directly or indirectly by the bushfire.

Those farmers, like former Western Dairy chairman Dale Hanks at Harvey, also had to dump between three and four days' milk production because milk tankers from their processor were not permitted to enter the emergency zone.

At the time Farm Weekly went to press, there were no reports of any dairy cattle having died in the fire or having to be put down after it.

But up to 200 beef cattle may have died.

A Department of Agriculture and Food (DAFWA) spokeswoman said veterinarians and other staff were carrying out livestock assessments where it was safe to do so, but there was no confirmed number yet of stock deaths.

"DAFWA is working to support a wide range of agribusinesses affected by bush fires in the South West," she said.

"The affected areas still require permits for vehicle access.

"Affected producers requiring urgent access for stock feed, fuel, livestock transport or other vehicles over the coming days should call DAFWA's helpline on 9780 6200.

"DAFWA will attempt to negotiate access approval with the relevant authorities.

"Please also call the helpline if veterinary assistance is required for livestock.

"The RSPCA will be assisting with companion animal - including horses - inquiries and can be contacted on 1300 2783 589."

WAFarmers has launched a fundraising campaign to help farmers affected by the fire.

President Dale Park urged people to donate cash through the GoFundMe account established by WAFarmers at https://www.gofundme.com/8gx38ezg.

"Cash is the most practical donation at this stage as people slowly start to assess the damage and determine what they need to repair their lives," Mr Park said.

"Once the fires are extinguished and the full extent of the damage can be determined, more information about how to support the affected communities will be provided."

WAFarmers is also co-ordinating donations of hay for livestock on 9486 2100.

The fire burned more than 71,150ha with a perimeter of more than 232 kilometres that stretched to the coast.

It claimed the lives of two men, aged 77 and 73, in their Yarloop homes on Thursday night.

A total of 143 properties, including 128 houses and other structures including sheds, caravans and community buildings, have been confirmed destroyed.