An Oakville winery has been fined for its failure to immediately notify authorities of an ammonia release at its winery, the Environmental Protection Agency reported Friday.

Diamond Oaks Winery was fined about $11,700 for taking a month to report the August 2006 incident at its Oakville Grade plant, according to the EPA.

In all, between 750 and 800 pounds of ammonia — a hazardous chemical that can irritate the skin, eyes and the nervous system — were released in the air after a pressure gauge and seal on a compressor motor failed, according to the EPA.

Diamond Oaks President Raj Maniar on Friday said the winery will pay the fine. “We did not file (the paperwork) with the right agency at the right time,” Maniar said.

“It was purely a mistake on our part,” he added, who stressing that no one was injured and that no ammonia entered the winery. The winery uses ammonia to cool the facility, Maniar said.

Under federal law, releases of 100 pounds or more of ammonia have to be reported immediately.

According to the EPA, a Diamond Oaks employee discovered the incident in August 2006, but the winery did not report the incident until September of that year.

EPA spokesman Francisco Arcaute said the winery should have immediately notified the agency’s National Response Center so that authorities could inform local fire departments and emergency responders, including hospitals.

In a written statement, Keith Takata, Superfund division director for the EPA’s Pacific Southwest region, said “companies have a responsibility to immediately report toxic chemical releases.”

The compressor that contains the ammonia is kept outside of the 26,000-square-foot winery, said Maniar, adding Diamond Oaks hired a consultant to interpret the state and other regulations dealing with the chemical.

According to the company’s Web site, the Maniar family began to purchase vineyards in 1977. The family owns a total of 550 acres of vineyards at four sites in the Napa Valley, Carneros and Alexander Valley. Most of the vineyards — about 330 acres — are in Carneros. The winery was purchased in 2003.