Temporary layoffs at Washington-based Weyerhaeuser could start next week.
According to union officials, the timber company plans to lay off workers at one of its four Longview mills. More than 500 people work there.
The company declined to comment, but earlier this month a spokesperson for Weyerhaeuser said layoffs were coming. He blamed the labor dispute at West Coast ports.
The International Longshore and Warehouse Union and the Pacific Maritime Association are negotiating a new contract.
Both sides have blamed one another for shipping delays at the ports.