EPA Victoria testing has shown the water quality in Laverton Creek is returning to normal and Cherry Creek was not affected at all after the chemical fire in Swann Drive, Derrimut on 10 July.
EPA and Melbourne Water are reporting back to local community groups and will remove the warning signs along Laverton Creek in coming days.
"Thanks to the hard work of all agencies involved in the response and reducing the impacts of contaminated firewater, our community and environment have fared better than expected from such a significant incident, with no reported impacts on fish or wildlife," said EPA Agency Commander Steve Lansdell.
"Our testing showed chemicals such as toluene, ethanol, acetone and surfactants (industrial detergents) were present on the day after the fire, but it is pleasing to see them dropping below any levels of concern in the week afterwards."
Mr Lansdell said heavy rain played a role in the outcome and was part of EPA's decision to issue precautionary warnings about water quality around the mouth of Laverton Creek and in the Altona Beach area.
"We'll continue to work with Fire Rescue Victoria (FRV), WorkSafe, Melbourne Water and councils as the clean-up of the fire site gets underway," he said.
Investigations into the fire are continuing, and the timeframe will depend on progress with clean up.
"EPA has taken a precautionary approach, even when chemical levels in the water turned out to be well below the level that could affect fish, invertebrates and other aquatic life," Mr Lansdell said.
"We will prepare a public science report in coming weeks once all sediment testing results are received to help explain all the monitoring and science advice EPA has undertaken throughout this incident," he said.
No bird or fish deaths have been reported.
