Thousands of fish have died after a fire at a bourbon whisky distillery in Kentucky led to alcohol-contaminated water entering rivers and streams.
About 45,000 barrels of bourbon burned in the blaze at the Jim Beam warehouse, where firefighters from four counties were enlisted to help contain it.
But over the weekend, officials said runoff from firefighting efforts had led to an alcohol plume in one river.
Wildlife officials say it is causing low levels of oxygen in the water.
The plume in the Kentucky River is estimated to be about 24 miles long (28km) and is travelling towards the Ohio River at around 0.6 mph.
Once it reaches the Ohio River - forecast for later on Monday - is it expected to dilute to safe levels.
"The bacteria in the water is going after the food source, which is the sugar in the alcohol and so they deplete the oxygen," said Robert Francis, who is managing the state's emergency response team.
"The fish start to become distressed, and they eventually die."
Crews are using barges to aerate the water, in an effort to boost oxygen levels for struggling fish.
Mr Francis added that the state knows how to handle bourbon spills and already has a procedure in place.
"We've had several occur in this state, so when this one occurred, we were just ready for it and knew what the actions were to take," Mr Francis said.
Officials plan to allow the fish to naturally decompose - causing no harm to river - and say the water is not dangerous to people.
Beam Suntory, Jim Beam's parent company, said in a statement that "with the fire extinguished and everyone safe, we are focused on minimizing and remediating environmental impacts".
"We have built berms at our site, to avoid further runoff to the nearby waterways, and we are conducting water sampling and water field screening to get real time results of water quality on the river, as part of a coordinated effort," the statement said.
In a Facebook post on Monday, the Kentucky Energy and Environment Cabinet said they are still surveying the area to estimate how many fish have died.
"We continue to see dead and dying fish," they advised.
"People using the Kentucky River in the area of the plume will likely see and smell dead fish."