Based on the latest assessment of the continuing and ongoing impacts of the pandemic, management concluded that there was no other option than to place Coal Valley in care and maintenance.
Chief operating officer Joe Micheletti said: "This is a very difficult call for us to make, however, we know it's the right decision in the circumstances and one that balances our duty of care to our workforce with the long-term interests of Coal Valley."
The company will pay severance to all affected employees.
"We will be transitioning to a small number of employees remaining on site to maintain the property and equipment, as well as to oversee all environmental responsibilities and compliance," said Stephen Love, Coal Valley's general manager.
Westmoreland's management team is working with all stakeholders on a phased reduction of production operations at the mine site, with the transition to full care and maintenance activities expected to occur within the September quarter.