What's that stinky smell around Santa Rosa?

Some people know it as the “Sonoma Aroma,” a not-so-gentle reminder that the North Bay was farm country long before it acquired its reputation as Wine Country.

A couple of times each year, local dairy farmers start pumping out their holding ponds to spread cow manure out on their fields. The resulting odor, which pervaded the air around Santa Rosa and as far north as Healdsburg on Wednesday, is a unique and unmistakable Sonoma County barnyard bouquet.

“It made me want to vomit,” said Shauna Eagleton, who caught the unpleasant odor at the PG&E office at Stony Circle in Santa Rosa where she works as a land surveyor. “It was very, very strong.”

Sue Ostrom, Sonoma County’s chief deputy agricultural commissioner, said the process of “manure spreading” traditionally occurs around the time of the end of the Sonoma County Fair.

“Depending on the direction of the wind, it will affect people differently,” Ostrom said. “It’s essentially being used to return nutrients to the soil.”

Ostrom said she couldn’t quantify exactly how much cow manure is currently being spread on Sonoma County fields.

Eagleton, a lifelong Santa Rosa resident who said she has lived near Petaluma, couldn’t remember the smell ever being this bad.

“I know what the dairies smell like,” she said. “This was 10 times worse - it was toxic.”

Tom Flannigan, a spokesman for the Bay Area Air Quality Management District, said Wednesday there have been no recent complaints made to the agency about foul odors in the area. Nor have there been any documented odor violations, he said.

But unpleasant whiffs were sniffed in places like Healdsburg, where it wafted over diners having lunch on the outside patio of The Parish Cafe on Mill Street, and up in the Mayacmas, where employees of Pepperwood Preserve noticed it on Wednesday afternoon.

“Staff was commenting on how bad it smelled outside,” said Adrienne Pettit, finance & administration director of the nonprofit ecological institute dedicated to science-based conservation and education, which is located some 30 miles northeast of Petaluma.

“I finally stuck my head out of the office and thought we had moved our herd of cattle to the pasture in front of the Dwight Center,” she said. “I left the office headed for Petaluma and realized the smell wasn’t attributable to our cattle. By the way, Petaluma didn’t smell like Petaluma tonight.”

The migration of the stench north seems to be in keeping with current weather patterns, according to the National Weather Service, which said winds have been blowing in a northerly direction in recent days. Typically, they said, breezes come in from the west this time of year.

Healdsburg winery sommelier Lydia Stafford said she got out of her car at Coddingtown Mall on Tuesday and the “stench kind of hit me in the face.

“We have tried to keep the windows closed in the house as to not let the ‘Sonoma Aroma’ waft its way in,” she said.

The smell has been a topic of conversation online with Twitter users making use of the hashtag, “#SonomaAroma.” One, who goes by the handle “Jess,” complained, “Santa Rosa smells like poop.”

Santa Rosa resident Tony Esposti posted his complaint on his Facebook page. “Thank you Petaluma for the sweet aroma in Santa Rosa. It’s a wonderful gift,” he wrote.