Councillors have unanimously backed a motion by Cr Peter Moran asking council staff to prepare a report on ways of encouraging future businesses and residents to help make the precinct a plastic bag free zone.

Cr Moran said plastic bags were "environmentally damaging and aesthetically not pleasing".

"Everyone knows I am not a proponent of the marina and that I am not happy to see a wetland being destroyed to build it, but if we are to build a $1.5 billion project we should make it the best facility it can be," Cr Moran said.

"If it is full of floating plastic, it will detract from the amenity, as well as pose an environmental hazard for marine life."

Cr Moran said it would be easier to convince a large supermarket and the 15-30 small shops proposed for The Waterfront to be plastic bag free before they entered the precinct rather than after.

Councillors Kellie Marsh and Paul Rankin suggested that the motion be changed to encourage biodegradable plastic bags.

However Cr Moran said that biodegradable plastic bags could also be a hazard in a marine environment.

Construction work on the $65 million second stage of the boat harbour is continuing, with 53 to 62 workers on site daily, all from the Illawarra.

The works undertaken by Illawarra-based contractor Coastwide Civil include excavation of the rest of the harbour basin - involving more than one million cubic tonnes of material - and construction of the harbour's edges.

Stage two is due to be finalised in February 2017.

The first boats are due to be moored in the harbour in 2019.

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