Geoff Mitchelmore is a mild-mannered former industrial chemist, not given to profanity, but even he admits that 16 years ago, the Kororoit Creek at Altona North was "a shithole".

It was an industrial wasteland of shopping trolleys, car wrecks, builders' rubble and weeds, a playground for motorcycle riders, drug dealers and snakes.

"I wouldn't let my kids come down. It was dangerous," he said.

The waterway had been a drain since colonial times, used to to dump abattoir blood, oil and other chemical nasties.