FILE - Steam is seen at the Longview Westrock mill, which makes cardboard materials including container board and corrugated containers, March 14, 2024, in Longview, Wash.
Jenny Kane / AP
Investigators from the government and social media have spent months trying to find out where a mystery smell that swept through Southwest Washington on its way to Portland in September originated.
Washington’s Department of Ecology confirmed Wednesday it had a likely answer for part of the stink: the Smurfit Westrock paper mill in Longview, Washington.
Longview is home to several paper mills and wood pulp facilities that use sulfur-based compounds to break down wood products.
In October, Westrock said it didn’t believe it contributed to the smell that had concerned residents in the roughly 60-mile stretch between Longview and Portland.
“Smurfit Westrock can confirm that no air permit violations occurred at the facility on Sept. 24, 2024, and there is no indication the Longview paper mill was the source of odors cited in complaints,” the company said in a statement to OPB at the time.
The state Ecology Department confirmed the company did not violate its emissions permits, but said it had concluded Westrock emitted a noxious stench on Sept. 24.
“Operations at the Westrock-Longview paper mill likely caused an increase in odors in Longview, Washington and nearby areas on Sept. 24, 2024,” the agency said in its statement. “However, we don’t have data to show the facility was the source for odors that caused complaints in Vancouver and Portland.”
Related: Recurring odor in Southwest Washington has residents searching for answers
The agency added it could not conclusively say if other sources also added to the smell.
While the answer does not definitively point the finger at Westrock for the odd odor, the Ecology Department said it could say for certain that the company did not emit chemicals in concentrated enough amounts to threaten human health or the environment.
The state agency used odor complaints, weather data, work done at Westrock that day and emissions data as part of its investigation.
“In general, odor investigations are challenging to address and are often inconclusive,” Ecology Department officials said in the statement. “However, Ecology’s report on this represents the agency’s best attempt to determine whether and to what degree the operations at the Westrock mill contributed to September’s odor concerns.”