Loch Lomond Distillers are reported to have lost around 60,000 litres from their warehouse in Catrine, Ayrshire after a leak went unnoticed in one of the company's giant vats.
The loss - the equivalent of 85,000 regular bottles - sparked an investigation by safety experts and environment watchdogs.
They discovered that most of the whisky had drained into the ground, while the rest found its way into the local River Ayr.
The Health and Safety Executive (HSE) and Scottish Environmental Protection Agency (SEPA) carried out an inquiry into the leak amid fears it was a potential danger to the public.
A SEPA spokesman said: "An investigation was carried out at the Loch Lomond Group bonded warehouse in Catrine, following a discharge of whisky from the facility.
"It's understood that due to a leak inside the building, a significant quantity of whisky managed to escape through the floor of the warehouse.
"It's likely the majority of the whisky was absorbed by the ground beneath the warehouse but a small amount did manage to enter the drainage system and discharge directly into the River Ayr.
"Following numerous assessments of the watercourse by SEPA officers, the discharge was not found to have had any significant impact on the surface water environment.
"As the facility is also regulated under the Control of Major Accidents and Hazards Regulations 2015, a joint investigation was carried out by SEPA and the HSE.
"As a result, a series of corrective actions have been issued to the operator to ensure this incident does not reoccur."
Both organisations have only just completed their investigation into the leak, which happened in June.
Whisky bosses have been told to tighten up their operation and safeguard against further spillages.
A Loch Lomond Distillers spokesman said: "We can confirm there was an accidental leakage of around 60,000 litres of blended whisky from a vat at our bottling plant at Glen Catrine in Ayrshire.
"Tests showed no evidence of alcohol in the River Ayr, no visible evidence of impact on wildlife and minimal traces of alcohol on the river banks.
"We've been working with both SEPA and the HSE to ensure that there is no recurrence."
This is the second time in five years there has been a major leakage of whisky at the plant.
In 2011, about 6,600 litres of stronger whisky spirit was spilled when the distillery was under different owners.
Most of the whisky leaked into the River Ayr and the company were fined £12,000 in 2014 after they admitted charges.