Environment Protection Authority Victoria (EPA) is responding to a grout discharge into Stony Creek, Yarraville.
Officers were notified of approximately 150m of affected water and are working with the relevant duty holder on the clean up.
EPA Metro Manager Dan Hunt said while any pollution was concerning, this was especially disappointing as the creek was just beginning to recover from the effects of the West Footscray factory fire.
“We know this is a blow to the community which has worked so hard to give the creek the best chance of rehabilitation,” he said.
“While the grout will make the water murkier it is unlikely to have a significant impact on the health of the creek, which was severely compromised by the fire run-off.
“EPA is investigating the discharge and will consider any enforcement action as appropriate under our Compliance and Enforcement Policy.”