In fact, it may take months into 2020 before Port Macquarie-Hastings Council can update the environmental data required to obtain a one-off licence from the state government to proceed with any opening strategy for the ailing waterway.

Council's most current environmental data for the lake is more than two decades old.

At the November council meeting on November 21, council voted in favour of obtaining a one-off licence from Crown Lands to open the lake. At that meeting, Cr Pinson said the lake had been deteriorating day by day, week by week, month by month.

She said opening the lake was not only the right thing to do but it was the expected thing to do by our community.

Now, before that licence is granted, council must conduct a review of environmental factors (REF). The last time this was done for the waterway at Lake Cathie was 1995.

"Do we have sufficient resources to expedite that matter if necessary," deputy mayor, Cr Lisa Intemann, asked at the December council meeting.

Director Melissa Watkins said no moves to open the lake will be made until a new REF is completed.

This drew dissent from the public gallery - "So nothing is going to happen until next year!" someone yelled from the audience.

"Nothing will happen to the lake this side of Christmas," general manager Craig Swift-McNair said.

"It will take months to prepare a new REF. The state government has said the information we have is not good enough and council has to start a new process."

In the meantime, signage has been erected at the lake's foreshore in the lead-up to the summer holiday season warning people not to swim.

Revive Lake Cathie president Danielle Maltman said it is "disappointing and disgusting" that a whole of community and government approach to finding solutions to saving the lake are not being taken seriously.

"What is happening in regards to on ground action saving the Lake Cathie-Lake Innes estuarine system - do councillors know? Because we do not," Ms Maltman asked councillors.

"I ask you do you know why community groups are being excluded from meetings?

"Council has specifically identified community stakeholders and has since hosted one meeting with all of us. However, we have been excluded from government stakeholder meetings since their inception, meetings that council convenes.

"In September council advised that identified community stakeholders would receive a communications plan from council. We are still waiting on this plan."

Ms Maltman supported the council's decision for a one-off licence to open the lake in the short-term while all the stakeholders looked at the holistic approach for the Lake Cathie-Lake Innes estuarine system. But that collaboration does not seem to include them, she said.

"As recently as yesterday there has been a change in language to potential opening the lake. Is there a reason for this change?

"Can council tell the public what has been applied for in their short-term licence and what is the expected time frame?

"We all agree on one thing, a long term solution is required to address the many issues of the Lake Cathie-Lake Innes estuarine system but in the short term surely we can show some care for our marine life and community members public health and implement action to mitigate current risks."

Cr Justin Levido questioned Ms Maltman's motives in challenging council about its alleged inaction on the lake's management.

"Do you believe council should be transparent in its dealings, and that people and organisations are transparent in their dealings with council?" Cr Levido asked Ms Maltman.

Cr Levido said he had heard Ms Maltman is seeking election to council in 2020 on a Revive Lake Cathie ticket that would be supported by Mayor Peta Pinson.

Ms Maltman said she hasn't had those conversations with Revive Lake Cathie.

Cr Pinson called order for Cr Levido and questioned the relevance of his question.

"It is relevant because groups like Revive Lake Cathie come to council and criticise us for not being transparent. People say to us we've got to be transparent - people need to be transparent in return," he said.

"It's important people need to know where groups are coming from when they speak with council."

He asked Ms Maltman again if she is seeking to run in the 2020 election on a ticket supported by the mayor.

Ms Maltman said, "in the interests of transparency", she has been asked by two councillors to run at the next local government election but has had no further discussions on the matter. She said Revive Lake Cathie has no plan to run a ticket.

The mayor asked Cr Levido where he heard this rumour.

He declined to answer.