Adjacent to John Day Dam was a large aluminum smelter. Making aluminum requires very high amounts of electricity, thus it was appropriate to build the smelter next to a hydroelectric dam. The smelter began operation in 1969 and changed hands many times over the years, it stopped operation in 2003. Currently the owners manage hazardous and solid waste at the site. Due to the nature of aluminum smelting, the site is likely to be highly contaminated with asbestos. See the satellite picture to get a sense of the size of the operation.

The only information I could find about the site came from the following two sources:

Washington state: fortress.wa.gov/ecy/gsp/Sitepage.aspx?csid=11797
Mesothelioma.com: www.mesothelioma.com/asbestos-exposure/jobsites/aluminum-plants/columbia-aluminum.htm