INDUSTRIAL pollution has been identified as the cause of recent contamination in Cabramatta Creek.
The creek runs through the Elouera bushland reserve in west Liverpool, feeding into Chipping Norton Lakes and joining the Georges River.
Sydney Water and Liverpool Council collected samples of the contaminated water for analysis.
Inspections were also carried out at industrial complexes that drain into the catchment area.
A council report on the investigation traced the pollution to a factory operating upstream from the affected site.
"Steps were taken to remediate the immediate area around the factory and to provide bunding to the work areas within the factory, to prevent future escapes into the stormwater system," the report said.
"While we believe it may have been the same material that was found in Maxwells Creek, we are not able to definitively make that claim."
Maxwells Creek is also within the Georges River catchment and the Liverpool district sub-catchment.
The 3km-long creek starts in Prestons and flows north to link up with Cabramatta Creek.
Liverpool councillor Peter Harle asked the council to explore practical, cost-effective steps to ensure possible industrial pollution could be traced with certainty.