Three of Weyerhaeuser Co.'s (WY) softwood lumber sawmills in Canada and one in western Washington will take periods of downtime due to poor market conditions. Mills affected are in Grande Cache, Alta., Carrot River, Sask., Chapleau, Ont. and Aberdeen, Wash. In a news release, the forest-products company said the downtime, which will take 60-70 million board feet out of Weyerhaeuser's system, is scheduled to begin in May and June. Weyerhaeuser said its other mills will fill customer orders while the company continues to take actions to improve operating efficiencies throughout its softwood lumber production system. Weyerhaeuser is a softwood lumber producer.