The Montana Pole and Treating site is located in Butte, Montana. A wood-treating facility operated on site from 1946 to 1984. During most of this period, a solution of about 5 percent pentachlorophenol (PCP) mixed with oil was used to preserve poles, posts and bridge timbers. Wood treating involved the application of the PCP solution to wood products in vats and pressure cylinders (retorts). Creosote was used as a wood preservative for a brief period in 1969. Site operators discharged hazardous substances from the pole-treating operations into a ditch next to the plant. The substances then flowed toward Silver Bow Creek. These activities contaminated soil, sediment, surface water and groundwater with hazardous chemicals. Following cleanup, operation and maintenance activities are ongoing.