The Office of Environment and Heritage will contribute $800,000 to a biobanking fund for the coastal nature reserve and will make ongoing annual payments to the council to implement a management plan for the site.

The council will contribute $96,000 to the fund over the next three financial years - an amount already committed for vegetation management works at the site.

Future of our botany lies in plant bank at Mt Annan: photos

Councillors will vote at Monday night's meeting on whether to enter into a memorandum of understanding with the office to establish the biobanking agreement.

Councillor George Takacs supports the funding, which will be used to control weeds and pest animals and restore native vegetation.

"In this instance it seems like a good result as it will allow us to maintain that site in perpetuity," Cr Takacs said.

"Some of the resources we're currently putting into that site can then go towards looking after another area. My recollection is that we actively manage only about 5 per cent of our natural areas - we need to actively manage more of them, and this gives us the opportunity to do that."

Councillor Jill Merrin will also endorse the memorandum, despite concerns.

"A biobanking grant often means that it's being used as an offset against land clearing that's happening somewhere else," she said.

"However, in this case at Puckeys the state government is going to retire the biobanking credits - which means it is not going to use them to offset development at another bushland site."

Cr Merrin said that Puckeys - between North Wollongong and Fairy Meadow beaches - was an important coastal wetland area.

"When you have a healthy wetland at the bottom of a creek like this, it absorbs a lot of flood water and filters pollutants out before it goes out to sea," she said.

"The vegetation also stabilises the soil and protects the inland from storms and sea level rises, and provides a fantastic habitat for native birds and wildlife."

In order to meet the requirements for the memorandum, the council would need to create a plan of management for the site which may mean re-categorising all or part of the site to Natural Area Bushland.

Currently Puckeys estate is categorised as an Area of Cultural Significance, due to the archaeological remains of Seafield House.

The council's endorsement of the memorandum would mean a biobank site would be established at Puckeys by April 30, 2015.