Despite Columbia Falls Aluminum Co. launching preliminary cleanup work, the U.S. Environmental Protection Agency is moving forward with its proposal to add the site to the National Priorities List, which would give the agency oversight and final say over removing contamination.

After a 60-day comment period, EPA spokesman Rob Parker said the agency received a total of 72 comments on the proposed Superfund designation. The National Priorities List is updated twice per year. After reviewing and responding to all of the comments, the agency will make a final decision whether to list the site.

“It’s probably, at the earliest, going to be early 2016, but the really important thing is that ... we’re moving forward with negotiations with the potentially responsible parties,” Parker said, referring to current and past owners of the site who may have contributed to the contamination. Part of the agency’s task would be compelling those parties to pay the costs of the cleanup.

A preliminary assessment of the site by the EPA was completed in 2014, and detected hazardous levels of numerous toxic substances, including cyanide, fluoride, arsenic, chromium, lead and selenium.

If and when the site is listed, the agency will begin a remedial investigation, meaning on-the-ground sampling of surface water, groundwater and soils to determine the extent of the contamination. After that, a feasibility study will interpret the results of the investigation and review potential cleanup options. Parker said that step include another opportunity for public comment.