1905: Asarco purchased the smelter and converted it to a copper smelter. Company adds arsenic recovery to smelter in 1912.
1917: Original smokestack replaced with one 517 feet tall, which Asarco called the largest in the world. Stack dispersed air pollution over a wide area of central and south Puget Sound.
1983: Asarco smelter, tidelands and nearby uplands area listed as part of the Commencement Bay Superfund site by the U.S. Environmental Protection Agency.
1985-86: Copper smelter and arsenic plant close.
1993: EPA earmarks a 950-acre area around the former smelter for ongoing cleanup.
2003: Studies expand pollution zone to 1,000 square miles in Pierce, King, Thurston and Kitsap counties.
2005: Asarco files for bankruptcy.
2006: State Department of Ecology, working with local health officials, starts taking soil samples from 1,000 play areas at schools, parks and child care centers. More than 100 have been cleaned up.
2007: State joins eight other states in a $1 billion lawsuit against Asarco for environmental damages and cleanup costs.
2009: State receives a $188 million bankruptcy settlement from Asarco, with half of it earmarked for the Tacoma Smelter Plume project. The rest goes to other former Asarco cleanups, including a former smelter in Everett.
October 2011: Ecology releases draft cleanup plan for the Tacoma Smelter Plume.
2012-13: Renewed soil sampling and cleanup to begin in Ruston, north Tacoma and southern ends of Vashon and Maury islands.
