Firefighters are investigating a diesel spill from a truck in the Homeworld Shopping Centre car park, Anketell Street, Greenway.
A small area of the car park has been closed off.
Some of the diesel has entered the nearby drainage system and firefighters are working to prevent any of the spill from entering Lake Tuggeranong.
Early estimates of up to 200 litres is believed to have leaked.
Officers from the Environment Protection Authority have also been called to the scene.
A revised estimate of up to 100 litres has leaked from the truck.
A minimal amount has entered the drainage system.
Firefighters will remain on scene whilst the Environment Protection Authority work to continue on the clean-up of the spill.