Environment Protection Authority Victoria is investigating a diesel spill that spread from the corner of Bourke and Shakespeare streets to Queens Parade in Traralgon and entered Traralgon Creek last week.
EPA officers, together with Latrobe City Council and the CFA, traced the pollution back to the vicinity of Shakespeare Street and worked with local businesses to stop and clean up the spill.
EPA acting Gippsland regional manager Stephen Lansdell said an unknown amount of diesel had entered wetlands and Traralgon Creek and impacted surface waters before absorbent booms were able to be put in place.
"The spill occurred due to a combination of a rupture in a diesel tank line and a break in a concrete stormwater pipe that passed through the site," Mr Lansdell said.
"The broken concrete pipe has now been replaced and the ruptured fuel line switched off so that no further diesel can discharge."
Mr Lansdell said the stormwater drain leading to Traralgon Creek had also been flushed with water that was then adducted by trucks and taken to an appropriate facility for disposal.
"The booms will remain in place near the stormwater discharge into Traralgon Creek to capture any residual diesel," Mr Lansdell said.
EPA's investigation will continue to determine whether any offences under the Environment Protection Act 1970 have occurred.
EPA urges members of the public to continue reporting suspected pollution to EPA on 1300 372 842 or at www.epa.vic.gov.au