The landfill's operators say that odor concerns peaked in 2013 and 2014 but have since been curbed by mitigation efforts. The spread of the fire, they say, has also been slowed to a rate of about six inches per day and is confined to one of the parts of the landfill farthest away from the known radioactivity at West Lake.

Knocke said in a statement: "After years of intensive ground water monitoring, there has been no evidence of off-site, downgradient impacts attributable to the landfill. As important, federal regulators have been clear that no one will ever drink or use the groundwater at the site. It will never be a public water source. The landfill is in a managed state. With the cooling barrier in the neck area now fully operational, more than $200 million in new treatment and monitoring infrastructure, and the EPA nearing completion of its permanent remedy for West Lake, these test results are unlikely to affect any regulators' plans. In addition, MDNR's letter will not change the ongoing, comprehensive groundwater monitoring regime and liquids management processes at the site."