IDAHO — A North Idaho lumber mill will close this summer as timber companies face strains from tight operating margins. Despite still earning a profit at the mill, Stimson Lumber Company will permanently close its Plummer facility by August. Stimson has leased the property from the Coeur d’Alene Tribe along U.S. Highway 95 since 2007, but CEO Andrew Miller anticipates no tenant will ever reopen the mill. …At its peak, the mill once employed around 100 workers and produced about 100 million feet of lumber a year, Miller said. Today, those figures have reduced to 22 and 35 million, respectively. …“We’ve seen it in western Montana where there used to be a lot of sawmills and pulp and paper mills, and a lot of that was based on the Forest Service being the primary supplier of timber,” Miller said. “But in the ’90s, they changed their focus.”