EVERETT, Wash. - A year after the city of Seattle required residents to recycle food scraps, the results have been impressive: in 2010, the city's contractor diverted 90,000 tons of Seattleites' banana peels, chicken bones and weeds out of landfills and converted that waste into rich compost prized in gardens.

But the process that helped the city set an all-time high recycling rate of 53.7 percent hasn't been without controversy.

The company turning that waste into compost has come under fire by citizens and others who complain of a pungent stench emanating from its two facilities located outside of Seattle. Cedar Grove Composting has gotten more complaints than any other company since 2007, according to the Puget Sound Clean Air Agency that regulates air quality in this region.

The battle over odors got messier this summer when a tribal official and a mayor from a town neighboring one plant appealed directly to Seattle to intercede with its vendor. And a community group calling itself "Citizens for a Smell Free Snohomish County" is also raising a stink.

A Washington state legislator stepped in to urge parties to agree to an independent study tracing the odor sources. Seattle city officials recently met with company representatives and said the city is willing to chip in money for such a study.

"We are eager to get the situation resolved for the environment out there and for the reliability of our processing system," said Timothy Croll, Seattle's solid waste director. Seattle is Cedar Grove's second-largest single customer.

Cedar Grove operates the largest composting facilities in the region and among the largest in the country. It takes yard waste and food scraps from homes and business throughout Puget Sound, processing about 344,000 tons last year at its facilities in Everett and Maple Valley. More than a third of it came from Seattle homes and businesses, while the rest came from cities in the region.

"They reduce our garbage rate because of all the organics they take out of the waste stream," said state Rep. Hans Dunshee, D-Snohomish. "On the other side, we can't have overwhelming smell driving people out of their houses. We've got to meet both goals."

Cedar Grove says it welcomes an independent odor study. The company acknowledges some of the odors are theirs, but it says numerous other sources in the area generate odors similar to compost.

Cedar Grove has invested millions to control smells at its plants, said company spokesman Laird Harris. The company has set up a computer-based odor monitoring program and its own inspectors are out logging odors, he said.

"There's clearly not a constant amount of odor leaving the facility at any time any day," Harris said. "There are periods when you have some but the periods tend to be short."

Since 2007, however, the clean air agency has received a total of 1,700 complaints - 500 for the Everett plant, and 1,200 at the Maple Valley plant. The company says an aggressive mailing campaign has made it easy to report odors as belonging to Cedar Grove.

The clean air agency fined the company a total of $169,000 for 17 violations - 14 at Marysville and 3 at Everett - in 2009 and 2010. Cedar Grove appealed those fines. Last July, the board upheld the violations but reduced the penalty to $119,000. The board said Cedar Grove "has at some points in time denied responsibility for the odors, directed responsibility towards other businesses, and been non-responsive to (violations)," but it credited the company for spending $6.5 million to reduce odors.

Cedar Grove is appealing to King County Superior Court.

"There's a very intense smell that needs to be taken care of," said Jon Nehring, mayor of Marysville, north of the Everett plant. He and Tulalip Tribal Chairman Mel Sheldon wrote to Seattle Mayor Mike McGinn in July asking for help. "The smell is awful. When the temperature starts to rise, it gets worse. It's a very distinct smell. It's a nauseous sweet silage smell."

Mike Davis, who founded the Citizens for a Smell Free Snohomish County, said at times he and his wife can't open their windows or be outside their Marysville home because of the smell. "It's pretty bad. It's not every day. It feels like standing in the middle of a trash pile," he said.

He and others want the company to fully enclose operations. They say a large indoor composting operation in southern California hasn't generated as many public complaints.

Harris says it's not practical to enclose the massive plant. He notes the state-of-the-art fabric-like cover is 98 percent effective at reducing odors.

The company plans to enclose the area where material is grinded. Harris said it extended the tipping building to allow large trucks to pull in and unload in an enclosed area.

One morning at the Everett plant, a Waste Management driver backed his truck into the enclosed building and unloaded yard clippings he'd picked up from homes in the nearby city of Arlington. Nearby, a truck mists the road to keep down dust.

Here wood chips are added to piles of yard and food waste to create the right balance of nitrogen and carbon. The pile is then grinded, stacked in neat massive piles and covered with fabric. Air pumped into the piles help break that organic matter into finished compost - a process of about 16 weeks. That compost is sold in bulk and by the bag at garden centers throughout the Northwest where it has been promoted by gardeners and others as a way to conserve water, suppress weeds and build healthy soil.

"It's made here. It's recycled here. It goes back into the same yards where it came from," said Susan Thoman, the company's business development director. "We do as much volume as we do because our citizens are green."

But Davis, who says the odors have affected the quality of life for many, said: "Green is great, but come on, let's do it responsibly."