Tens of thousands of gallons of fresh cabernet sauvignon wine poured into the Russian River in Sonoma County on Wednesday.

The wine -- enough to fill more than 500,000 bottles -- spilled from a Rodney Strong Vineyards’ storage tank at the Healdsburg winery, made its way into Reiman Creek, the river’s largest tributary, and eventually drained into the river.

It’s likely the biggest wine spill in county history, and certainly in the past 20 years, said Don McEnhill, executive director of nonprofit Russian Riverkeeper, noting he couldn’t recall gallons of this magnitude reaching the river.

A roughly two-foot oval door near the bottom of a 100,000-gallon Rodney Strong blending tank somehow popped open about 1:30 p.m. Wednesday and spilled from 46,000 to 96,000 gallons of wine, officials with the Governor’s Office of Emergency Services said Thursday.

Local and state water quality and fish and wildlife officials are investigating to determine any negative effects to the river ecosystem and whether the winery violated water quality rules. Investigators with the North Coast Regional Water Quality Control Board and California Department of Fish and Wildlife were on-site Thursday to determine the extent of environmental damage.

Charles Reed, a water board supervisor, said the higher river water level from recent rain likely helped dilute the wine that could have been attractive to smaller organisms fish use for food.

Rodney Strong spokesman Chris O’Gorman said the winery is conducting an internal investigation and cooperating with authorities. “We are deeply concerned and are doing everything in our power to protect our waterways,” O’Gorman said.

Aerial footage Wednesday afternoon from Sonoma County Sheriff’s Office Henry 1 helicopter showed much of the wine rushed through the creek and spilled into the river, lining the riverbank for several miles downstream. The helicopter tracked the spill as far south as Riverfront Regional Park within a matter of hours.

While it’s early in the investigation, it’s technically a code violation to release any substance into the water that could harm fish, said Eric Laughlin, spokesman for fish and wildlife agency’s office of spill and prevention response. Due to the nature of the accident, the county water quality board already identified two permit violations, although what enforcement will be for those is not yet determined, Reed said.

Results from water samples taken to measure potential fish kill are expected in a few days, he said, and a full report on the wine spill should be completed in two weeks.

The wine initially drained into an inlet on the floor of the Rodney Strong winery production building, and rushed through hundreds of feet of underground pipe that empty into four wastewater ponds on the property. When those ponds filled up, wine runoff began pouring into the creek, an industrial brook that runs through the vineyards. As the drains became overwhelmed, wine also streamed out of the building and into the creek.

Rodney Strong workers used two vacuum trucks to clean up the spill on its property, and tried to quickly assemble a temporary dam to halt the spillage into Reiman Creek, said Sonoma County Fire District Battalion Chief Mike Elson. Cal OES officials said about 20% of the initial spill was contained.