A creek in Melbourne’s west is so heavily contaminated with black oil that it will be weeks before it’s cleaned up, Melbourne Water has said.

The Environment Protection Authority was called to the Paisley Challis Drain in Williamstown on Tuesday morning after residents reported that the creek had turned black and there was a pungent, chemical-like odour in the area.

The Paisley Challis Drain was heavily contaminated on Tuesday. Credit:Matthew Miller

Melbourne Water spent more than 12 hours at the site on Tuesday afternoon to clean and contain the spill, and returned on Wednesday, but it has confirmed that clean-up efforts would last “several weeks”.

“An excavator, booms and vacuum trucks are on site to stop the pollution spreading,” a Melbourne Water spokeswoman said.