Debate about the technique however, continues to divide a community who have traditionally expected the excavation of a channel, used in lake openings by council over many years, will do the job and do it quickly.

This time around, council and councillors have remained conscious of the longer-term benefits of any action after the ravages of drought were followed by bushfires and then flooding. And for more than 18 months, it has played a to and fro game with the state government, the community and even each other, to come to a satisfactory resolution.

Read more: It's happening: Contentious lake scrape locked in for Friday

Mayor Peta Pinson, a long-term advocate for excavating a channel, made one last attempt at this month's council meeting to push for this option.

She said council had not shown leadership on the issue, had not met the community's expectations on the management of the lake and had the opportunity to end the "lunacy" and get the job done.

"You just can't push the envelope anymore. The community is crying out for council to take some leadership and create an excavation to allow the lake to become saltwater again," the mayor pleaded at the meeting.

"I am just requesting councillors, for goodness sake, can we end this lunacy now and open this lake."

Councillors instead, guided by the recommendation they were required to seek from Crown Lands, DPI-Fisheries and National Parks and Wildlife as a condition of a 12 month short term licence to open the lake for flood mitigation, opted for a scraping of the sand berm to a depth of 1.2m.

Both community advocacy groups, Revive Lake Cathie and Saving Lake Cathie, will no doubt be watching closely as the first trickle of water moves later today and how Mother Nature may or may not take the matter into her own hands. Both have agreed that sand grading of the lake ocean interface lower than the 1.6m opening trigger should alleviate public health and safety concerns due to flooding of private and public infrastructure issues in the short term.

Deputy Mayor Lisa Intemann, who was one of six councillors who voted in favour of a lake scrape, said the depth of today's action is crucially important in protecting the lagoon in the long-term.

"Ironically, council first applied to open the entrance back in November under serious drought conditions and very low water levels," Cr Intemann said.

"Yet six months later here we are and finally approved to open under emergency flood conditions, not drought. This is Australia.

"Historically, council has opened at 1.6m AHD (above sea level) by digging a fairly deep channel. But this has tended to close up quickly, like the last opening in 2018 which let out a lot of water from the lake system but quickly closed.

"Council staff recommended opening the entrance by digging a channel dug down to 0.8 metre AHD - heights are important here.

"On the other hand, specialist NSW government officers recommended not digging, but just scraping the sand berm a bit, only down to 1.6m AHD.

"It's important to note that at 1.6m AHD there is already some flooding of footpaths, parks and a few homes, and that's the height the lagoon is at now.

"So I don't see how the 1.6m proposal offers a solution to anything.

"Now the records suggest that footpaths start getting flooded at 1.4m AHD, so clearly we need to go down to at least that height above sea level.

"And at the other end of the scale, it's my understanding that we've recently found that acid sulphate soils are activated if the Lake Cathie water level goes below 1m AHD. So we don't want that.

"Based on those figures we want the water level somewhere between 1m and 1.4m AHD, which is probably why six of the eight councillors decided that the opening should scrape down to 1.2m AHD to alleviate flooding and prevent acid sulphate pollution.

"Considering the known facts, I was surprised that the mayor opposed the 1.2m AHD decision, wanting us to go down to 0.8m AHD or nothing,

"Granted, the 'opening' has never been done like this before so it's experimental. But its supported by some common sense logic and should work."

Cr Intemann said the action will succeed if it prevents flooding over the longer term, with the scraped channel staying open and not quickly closing up.

"We shall see, and re-think if necessary," she said.

Council still retains a 12 month short term licence from Crown Lands to open the lake if flooding persists.

Read more: Councillors make final decision to take action on lake

Council is also preparing a Coastal Management Program (CMP).

In 2016, the NSW Government introduced a new framework to manage the coastal environment in an ecologically sustainable way. The cornerstone of this framework, the Coastal Management Act 2016, contains provisions that should be followed to develop long-term strategies for the management of the coastal zone.

The Coastal Management Program (CMP) will set the long-term strategy for the coordinated management of the coastal zone. It will achieve the purpose and objectives of the Coastal Management Act. It aims to provide a framework for management of the coastal zone, which acknowledges and reflects the needs of the coastal area but balances this with the reality of the competing needs of the region.

The program will identify priority solutions to coastal management in Port Macquarie-Hastings, including the broader issues of the Lake Cathie estuarine system.

"I encourage people to get involved in the upcoming first stage, which is the scoping study to decide what issues should be covered in depth by the management program. For example, the highly controversial prospect of re-closing Lake Innes, adjoining Lake Cathie," Cr Intemann said.

Council's draft Coastal Management Plan Scoping Study will now go on public exhibition.

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