The agency's senior vice-president, Roberta Ellis, said it will now be up to Crown counsel to determine if charges are pursued under the Workers Compensation Act.
"Four workers lost their lives, 42 workers were injured, some of them extremely seriously," she said.
"When we finish our investigation into cause and turn our mind to consequence, these are serious matters and there are potentially very serious consequences."
But Ellis stressed the WorkSafeBC investigations are not linked to any possible criminal charges, and there are no criminal investigations underway.
It will now be up to Crown prosecutors to sort though thousands of photographs and hundreds of pages of information to determine if they will lay charges.
WorksafeBC can impose penalties on employers only, not individuals, but a referral to the Crown means the courts can impose higher fines and jail time on individuals if they are charged and convicted.
If the Crown does decide to lay charges, the sawmill companies and the individuals who run them could face fines of up to $600,000 and up to six months imprisonment under the Workers Compensation Act.
The B.C. Federation of Labour wants the Crown to look beyond WorksafeBC violations.
"If it was the case the company was negilgent, then there should be criminal charges and they should face jail time," said federation president Jim Sinclair.
Four killed and 42 injured
Two workers were killed and 20 more injured after an explosion and fire destroyed the Babine Forest Products mill in Burns Lake, B.C., in January.
Three months later, two people were killed and 22 workers injured after an explosion and fire at the Lakeland Mills sawmill in Prince George, B.C.
The two mills are owned and operated by separate companies, but wood dust levels were flagged at both sawmills as a possible fuel source.
A scientific analysis commissioned by WorksafeBC earlier this year concluded dust from pine beetle-killed wood could have contributed to the fatal explosions at both mills.
In April, WorkSafeBC released inspection reports for the Lakeland Mills sawmill, dating back to 2007, which show inspectors had repeatedly flagged dust levels at the mill as a concern.
Hampton Affiliates, the company that owns and runs the mill in Burns Lake, has said it intends to rebuild – provided certain conditions are met.
Those conditions include adequate timber supply, and if the company is able to work out agreements with the community of Burns Lake and area First Nations. The company has said it will make the final decision on whether to rebuild in December.