Cedar Grove Composting, the region's largest processor of yard waste and food scraps, must pay $119,000 in fines for odors from its Maple Valley and Everett composting facilities, a state hearings board has ruled.

Cedar Grove Composting, the region’s largest processor of yard waste and food scraps, must pay $119,000 in fines for odors from its Maple Valley and Everett composting facilities, a state hearings board has ruled.

The Pollution Control Hearings Board upheld 17 violation notices issued by the Puget Sound Clean Air Agency in response to complaints by neighbors who said the smells forced them indoors and in some cases nauseated them.

But, noting the company has invested $6.5 million in equipment and processes aimed at controlling the stench, the pollution board knocked $50,000 off the original $169,000 fine for those violations in 2009 and 2010.

“Although Cedar Grove expressed reservations about whether it was really the source of many of these odors, it still has moved forward in good faith to address these odor concerns,” the three-member panel wrote in an order Thursday.

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Cedar Grove spokesman Laird Harris said in a statement Monday that the company was pleased the fine was reduced. “However, we disagree with several other aspects of the Hearings Board’s decision, which we intend to appeal,” he added.

Laird said the company would work with the Clean Air Agency and other regulatory agencies to establish an odor-monitoring program that is scientifically based “and differentiates between odor sources.”

In a statement, Marysville Mayor Jon Nehring said the board’s decision was “a step in the right direction, and we hope that it will push the company to do the right thing and take care of its strong odor impacts.”

“It’s about time,” Mike Davis, a Marysville resident and founder of Citizens for a Smell Free Snohomish County, said in a statement.

“We’ve been waiting for someone to hold Cedar Grove accountable for their noxious odors. We’re tired of Cedar Grove denying any responsibility and blaming everybody else while people all around the region can’t even enjoy their own yards because of the huge stench,” Davis said.

The pollution board rejected the company’s arguments that Clean Air Agency inspectors lacked adequate training to determine the source of odors and that in some cases smells came from other sources such as landfills or a sewage-treatment plant.

Cedar Grove consultant ERMAS (Environmental Reporting, Monitoring and Solutions of Everett) concluded last year that less than 1 percent of the odors reported by neighbors of the Everett composting plant actually came from the property.

Cedar Grove began accepting food waste in 2004 — a change that “did increase Cedar Grove’s challenge in managing composting odors,” the pollution board wrote.

Keith Ervin: 206-464-2105 or kervin@seattletimes.com