IT COULD take days to determine whether Queensland Alumina Limited's caustic spill into the Gladstone Harbour caused damage to marine life.
A probe is under way by the Department of Environment and Heritage Protection after sodium hydroxide spilt into the Gladstone Harbour from a vessel at QAL's wharf late Sunday night.
Information about the caustic spill was not released until 5pm on Monday when the department found there was potential for risk to the harbour environment in its initial assessment.
EHP has no legislative obligation to tell the public about reported pollution, but initial assessment found potential for environmental risk to the harbour.
"Any time an EHP risk assessment in response to a pollution event identifies value in making a public statement, EHP issues a media release as soon as possible," a department spokesperson said.
Yesterday a department spokesperson said investigations in and around the harbour showed no evidence of the chemical nor environmental harm.
But he said indications of harm, including fish kills, were sometimes not immediately apparent.
"It is important to realise that impacts on marine life can take time to appear," the spokesperson said.
"Fish kills, for example, can take more than 24 hours to become visible, with longer lag times for other marine life that may have been stressed through this pollution event."
EHP officers conducted a site assessment at first light on Monday and have since completed onshore investigations.
It's not the first environmental woe for the major Gladstone industry player, which has copped hundreds of thousands of dollars worth of fines for previous breaches.
The alumina refinery was fined $400,000 in the Gladstone Magistrates Court for a large-scale caustic leak in June 2015.
Three years earlier it was fined $125,000 after the company pleaded guilty to one charge of unlawfully causing serious environmental harm. During the November 27, 2012, event sodium hydroxide aerosol sprayed into the air for about an hour.
QAL has said it takes its environmental responsibility "very seriously".
Update your news preferences and get the latest news delivered to your inbox.