MARYSVILLE — A 13-month study of odors in the Snohomish River Delta by the Puget Sound Clean Air Agency has done little to identify the source of noxious smells that have plagued Marysville and north Everett for years.

Representatives of Cedar Grove Composting, which has a facility on Smith Island in north Everett, were first to respond to the recently released results of the study, but representatives of other organizations — including the city of Marysville and the Puget Sound Clean Air Agency itself — soon offered follow-up responses of their own to dispute Cedar Grove’s characterization of the study results.

Cedar Grove Vice President Susan Thoman’s initial press statement touted the study results as a vindication of sorts for Cedar Grove, pointing to the multiple sources of odor that were identified, and citing the modeling results which showed that, during one quarter of the study, odors from the Marysville waste water treatment plant reached 24.9 odor units at the weather station in the center of town, compared to 3.7 from Cedar Grove. The study by Odotech defined 5.0 odor units as discernible to the human nose.

Joanne Todd, communications supervisor for the Puget Sound Clean Air Agency, pointed out that Cedar Grove was still one of the top three sources of odors recorded. While Cedar Grove came in third for the strongest single-incident odors, behind the Marysville waste water treatment plant in second and the Everett sewage treatment plant in first, data from Odotech’s e-noses placed Cedar Grove first as the source of the most persistent odors, with the Everett and Marysville plants coming in second and third, respectively.

Todd likewise relayed the observations of volunteers in Marysville and north Everett, who reported 122 instances of compost smells and 43 instances of fresh yard-and-food waste smells during the time that the odor study was conducted.

“Our volunteer sniffers were trained to spot the differences between compost and fresh waste, versus sewage and biogas,” Todd said. “The question became, though, if these odors are being steadily released all the time, why are they only noticed by people at specific times? When we compared those times to our meteorological data, we found that the volunteers’ recordings of strong odors overlapped 90 percent of the time with calm winds. Maybe certain smells move through the topography like rivers.”

At the same time, Todd joined Cedar Grove in lamenting that the city of Marysville had not agreed to participate in the study by having e-noses placed at the city’s waste water treatment plant. Marysville Mayor Jon Nehring had previously questioned the credibility of Odotech’s e-noses, since Odotech itself was already a vendor for Cedar Grove.

Gloria Hirashima, chief administrative officer for the city of Marysville, nonetheless touted the odor study’s executive summary, echoing what Todd cited about how often the human “sniffers” detected the scents of compost and fresh waste.

“Those were the most prevalent odors in their observations,” Hirashima said. “We’ve never denied that there are various odors present in the area, but so few of the rest of them are what our citizens have called to complain about.”

While the city of Marysville has its own odor expert reviewing the results of the odor study, Hirashima deemed the Puget Sound Clean Air Agency to be the regulatory agency on point for this issue.

“We’ll be looking to them for the solution to this problem,” Hirashima said.

Jim Kneeland of Pacific Public Affairs, also speaking for Cedar Grove, downplayed the data from the human volunteers versus that of Odotech’s e-noses, framing it as a matter of arbitrary judgement versus scientific method.

“It’d be like if we told state troopers that we were going to take their radar away and have them eye-judge how much drivers might be speeding,” Kneeland said. “About 70 percent of the complaints in the third quarter came from only three out of the 12 participating community members. That’s not a sufficient cross-section. Between its campaign with Strategies 360 and the fines that were imposed against it, the city of Marysville has spent about $1 million of the taxpayers’ money on this cause, rather than on controlling their own odors, and as long as they keep doing that, they’re never going to get to the real source of the smell.”