An excavation of a channel, as has occurred in previous lake openings, will not occur. A push by the mayor to dig a 135m long, six metre wide channel to a depth of 0.8m was defeated.

Port Macquarie-Hastings councillors debated their options at Wednesday night's (May 20) council meeting after receiving a recommendation by DPI-Fisheries and National Parks and Wildlife Service (NPWS) to take a more environmentally sensitive approach to managing the waterbody.

All councillors, except for Cr Sharon Griffiths and mayor Peta Pinson, agreed scraping the berm as per departmental advice, was the most appropriate option.

Cr Peter Alley successfully put forward a plan to bring the sand berm back to 1.2m AHD as it provides the best balance for the environment and the community while protecting council infrastructure assets such as footpaths.

A scrape to 1.2m should release enough water to address flooding.

The general manager will also write to the Minister for Water, Property and Housing to confirm that council's ongoing physical responsibilities for the management of the Lake Cathie waterbody will be limited to flood mitigation, stormwater drainage and community protection only.

Council will make clear to the state government that any actions outside of this scope including public health issues and complaints about water quality, colour, mosquitoes, fish kills, fish habitats, ecology of the waterway, salinity, acid sulphate soils, pollution and water safety, will be directed to Crown Lands as the owner of the waterbody.

Cr Alley said the community must acknowledge the time council has invested in the management of the lake and this final decision is measured.

"Never let anyone ever say again that council is not active on the issue of Lake Cathie," Cr Alley said.

Cr Alley was critical of the state government for pushing council to meet additional requirements following Crown Lands' provision of a short-term 12 month licence to open the lake for flood mitigation.

Council had to seek additional recommendations from DPI-Fisheries and NPWS before making a final decision on the most appropriate course of action.

"In April we reached a point where we could open the lake under the same terms and conditions we have done many times over last 25 years," Cr Alley said.

"We prepared our paperwork, we submitted it early this month and at the eleventh hour approval was conditional. The requirements have changed. It is typical of what the state government has been doing all the way along in this issue."

Cr Alley said despite this, it would be irresponsible for council to ignore the advice of DPI-Fisheries and NPWS.

That advice raised concerns about the potential adverse ecological impacts of excavating a channel.

It said artificial entrance openings of ICOLLs, such as that proposed in Lake Cathie, can lead to immediate, unintended ecological impacts such as large scale fish kills.

In addition, poorly timed artificial openings, such as those occurring before periods of drought, can cause long term low-level, hyper-saline, high temperature water which can also contribute to adverse ecological impacts such as fish kills and habitat loss, DPI-Fisheries advised.

Cr Lisa Intemann said a scrape to 1.2m will allow council to watch how the lake responds, rather than risk draining the waterbody without an assurance there will be future rainfall or velocity in tides to maintain a healthy water level.

Cr Intemann said council still has the short term Crown Lands licence for a flood mitigation lake opening for the next 12 months as a back-up.

"We do have an opportunity to do this again this year should that prove necessary. It is a balancing act and 1.2m seems to balance those issues."

Under the short term licence, council is permitted to enter the land for the purpose of emergency opening works, in the event of flooding only. The trigger point for an emergency opening is 1.6m.

Mayor Peta Pinson, who has long advocated for excavating an opening, did not support the decision. She said the "lunacy" around the indecision on opening the lake must end.

"This community has had expectations for us to act. The expectation came about as result of our opening strategy. Right or wrong, over many years, council has been responsible for the intermittent opening of this lake. It has become an expectation of the community this will happen," Cr Pinson said.

"We have got to a point where I have realised that we are but one stakeholder. There are many other stakeholders in management of the lake. We don't own the water, we don't own the fish, we don't own the coastline ... we don't own the vegetation in the lake or estuary system, yet we are expected to manage it.

"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

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

Cr Alley said it has been a complex issue to manage.

"The community were rightly concerned when the lake water levels were very low. The community wants there to be water in the lake, they don't want it flooding. They don't want it too low and they want it to be healthy," Cr Alley said.

Cr Rob Turner said it would be a devastating outcome if the lake were excavated and it could not revive swiftly enough for the spring holiday season.

Spokesperson for Saving Lake Cathie Stewart Cooper said the community will be watching closely to see how the berm scraping will work.

"This complies with the licence from Crown Lands but importantly minimises the risk of letting too much water out of the lake, while lowering the lake level so it is not impacting Aqua Reserve and people's properties," Mr Cooper said.

"Unfortunately council currently has no responsibility in the lake, other than for flooding, since the new legislation came into effect in July 2018.

"The licence is for 12 months and can be graded further if required. If you go too far you can't put the water back. Given the current level of siltation in the system there is considerable risk of a deeper channel letting too much water out.

"It is critical that the focus now move to the Coastal Management Plan.

"The Coastal Management Plan can address issues in the lake for the long term health and sustainability of the entire lake system."

The Revive Lake Cathie advocacy group supported the mayor's statement that the waterway is the "unmanageable lake".

The group believes scraping should be in a north-south direction and not east-west as previously undertaken.

"Revive Lake Cathie have been strong advocates of regular scraping of the lake/ocean interface or berm, since inception," a spokesperson said.

"It is supported by the world's leading estuarine specialists such as Colin Creighton AM and Dr Deborah Geronimi.

"In fact, should scraping have been implemented since Revive Lake Cathie's formation, the lake would not be in its current condition.

"The decrease (in lake height) from 1.6m to 1.2m AHD should alleviate public health and safety concerns due to flooding of private and public infrastructure issues in the short term."

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