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Toxics Cleanup Program

Tacoma Smelter Plume

Sources of Contamination

On May 12, 2004, Ecology named Asarco, Inc. as the potentially liable person for the Tacoma Smelter Plume contamination.

Ecology evaluated information as to the possible source or sources of the regional-scale contamination, and compiled this information in a Credible Evidence Report. Ecology reviewed several factors, including:

  • Pathways – there is a reasonable pathway from the smelter operations to regional soil contamination
  • Spatial patterns – the pattern of arsenic and lead contamination is
    closely linked to wind patterns and distance from the smelter
  • Trace Element Patterns – other metals released from the smokestack are found with arsenic and lead, and found to be closely correlated with the arsenic and lead concentrations
  • Consistency with Other Smelter Studies – the contamination patterns are very similar to those seen around other smelters worldwide
  • Absence of Other High-Emissions Sources – the Tacoma smelter appears to be the dominant regional source for arsenic in Puget Sound; no other source can be identified with regional-scale impacts.

Published Reports

The information is documented in the following reports: