Wollongong Greens councillor Cath Blakey is calling for strict compliance to environmental conditions for the recently approved Port Kembla floating gas terminal to ensure the sea is not polluted by cooled, chlorinated water.

Key points:

• A new floating LNG terminal approved for Port Kembla will use sea water to help warm gas back to room temperature
• The condition is the water cannot be released back into the harbour at fewer than 7 degrees below ambient water temperature
• Squadron Energy says it acknowledges the "strict requirements" around environmental guidelines covering the marine environment

The $250-million project was approved by the NSW Department of Planning, Industry and Environment in April 2019 then this year placed on the NSW Government priority list to be fast-tracked.

Councillor Blakey said sea water was used to bring the liquified natural gas (LNG) back from minus 161 degrees to room temperature, while chlorinated water was used to stop barnacles growing on the pipes.

"So there is a condition on their discharge licence that the cold water discharge can only be 7 degrees lower than the ambient temperature of the water in the receiving body, so in the harbour," she said.

"This will have to be strictly monitored to make sure that we don't have cold, dense chlorinated water falling to the floor of the harbour.

"It is planned that if it's done well it should mix in with the harbour water and we won't get a concentrated cold water pollution problem."

Shoalhaven-based marine biologist Pia Winberg said, in general terms, any measure to change water temperature could have a significant impact on fish species and underwater sea life.

"Changing the temperature is the big effect and it will have an impact on our local ecology if it's done outside the tolerance of a whole range of organisms including the seaweeds," she said.

She said a more effective way of getting rid of barnacles growing on pipelines may be to use hot water treatment rather than chlorine.

Approved environmental guidelines followed

NSW Planning said the approvals adhered to strict environmental guidelines to ensure the impact on the marine environment was minimised.

The owner of the gas terminal, Squadron Energy, has also emphasised its commitment to meeting strict environmental guidelines.

"Australian Industrial Energy has been through a rigorous approvals process for its Port Kembla Gas Terminal and was granted a development consent by the New South Wales Government," Squadron Energy spokesman Stuart Johnston said.

"We acknowledge the strict requirements of our development consent, including the environmental guidelines around the marine environment, and are committed to meeting these over the lifetime of the project."

A caller to ABC Radio, local architect Andrew Conacher, said it was too late for Wollongong City Council to raise such concerns as the gas terminal had already gained approval.

"Have they been bypassed? Did it go to council at all or did it just sort of slip through to the keeper?" he asked.