Councillors unanimously supported to seek further expert advice from the Department of Primary Industries and Environment (DPIE) on any further adverse impacts on the lake should it be dredged; and when beneficial to do so, make a request to Member for Port Macquarie Leslie Williams to fully fund it.

The matter was raised at the December 9 ordinary council meeting.

Mayor Peta Pinson said while the lake is loved by the community, there has been a serious environmental impact on the health of the waterway as a result of drought, followed by flooding.

"After 90 years of tampering with this lake we are in a bit of an environmental mess here. While I want to see our community provided with a beautiful lake ... we cannot deny we do have an environmental situation happening here," Cr Pinson said.

"The Member for Port Macquarie Leslie Williams has reached out to us and made a suggestion to dredge the lake where we have a large amount of sand in the middle of the lagoon.

"This dredging, it was recognised (at a recent stakeholders meeting), would have absolutely no benefit to the health of the lake, and I acknowledge that.

"We do have a situation however, just around the corner on Illaroo Road, where we have significant erosion happening. It is being monitored by staff.

"The ability to dredge the lagoon is ours to have if we chose to do so. We do have a development application that's approved through the state government to allow us to do that.

"It would be improper of us considering the fragility of the lake at this stage, to simply dredge for dredging's sake. I have it on good advice that Illaroo Road is not at a point that it's critical."

Cr Pinson said there will come a time when the lake will require dredging and it would be wise of council to seek expert advice from DPIE now about the possible impacts on the waterway if it chose to proceed.

"On top of that there is roughly a $350,000 expense to dredge and that is an expense that shouldn't be burdened on our ratepayers," Cr Pinson said.

"If future dredging were to happen, I would certainly be requesting (Mrs Williams') assistance in that regard."

Deputy mayor Lisa Intemann supported the mayor and agreed with the advice of experts that dredging the lake is of no benefit at this stage.

"I understand there is likely only to be 20,000 cubic metres of sand that could be dredged from the lower lake system at this point in time and that would not make a significant difference to the shoreline," Cr Intemann said.

"There is no dramatic need for it. I think it was absolutely agreed at the stakeholder meeting we must step back a little bit and do studies of the lake system before we do any intervention."

Cr Pinson said it is important council forge ahead with developing its Coastal Zone Management Plan (CZMP).

"The lake is loved by our community. I congratulate every community member for their commitment to ensuring that the lake is restored holistically back to a natural environment, but it can also be a recreational environment," Cr Pinson said.

"It's about finding that balance. The drought has changed our lake. It needs healing by working with the coastal management plan as to how we are going to interact with our lake into the future and by not messing with it at the moment. For every action we do, there will be a reaction."

The state MP formally requested in a letter to the general manager that council give consideration to the dredging of Lake Cathie lagoon in the coming months for the purpose of beach nourishment on Illaroo Road.

The current Lake Cathie CZMP indicates that council can undertake periodic dredging of Lake Cathie lagoon and place this material on the beach adjacent to Illaroo Road, however the CZMP also notes that dredging would be constrained by financial factors.

Mrs Williams said the state government has funded dredging at the lake in the past and if council favoured the action, she would "advocate for financial assistance".

Historically dredging has been undertaken by council on average every 10 years although the last two dredging events took place in 2014 and 2018.

A council report said in order to undertake dredging and nourishment works there are five main considerations to be considered, which include DA approval, licences, permits, funding and procurement of a contractor through a formal tendering process.

Council staff have been monitoring the sand loss on the fore-dunes adjacent to Illaroo Road over the past few months and acknowledge that beach nourishment works would benefit this location. However, the reports says it is likely there will be significant costs and further adverse environmental implications due to the current condition of the lake.

Council staff attended the Revive Lake Cathie stakeholder meeting in November, where Professor Scott Johnston, Southern Cross GeoScience, explained the current iron floc event in the lake.

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When discussing possible actions to improve the lake he indicated that dredging the lake at this time would not assist to remove the iron floc and that it should not be considered as it would likely have a whole raft of other impacts on the lake system.

At its May meeting, councillors agreed to scrape the berm at the entrance of the lake, opening it to the ocean. This action provided partial relief and the lake subsequently closed again.

Councillors also agreed at the time that the general manager to write to the Minister for Water, Property and Housing confirming that council's ongoing physical responsibilities for management of the Crown owned Lake Cathie waterbody are strictly limited to the responsibilities of flood mitigation, stormwater drainage and community protection only.

DPIE has confirmed that most of the Lake Innes/Lake Cathie system (the two lakes are joined by an artificial channel) is located within the Lake Innes Nature Reserve. The reserve is managed under the National Parks and Wildlife Act 1974 and is under the care, control and management of the NSW National Parks & Wildlife Service.

Crown Lands (within the Department of Planning, Industry and Environment) is the owner of a section of the bed of Lake Cathie, east of Ocean Drive where the lake interfaces with the ocean.

Crown Lands' involvement in managing the system is largely confined to authorising council to undertake entrance opening and dredging activities in this part of Lake Cathie, east of Ocean Drive.

In May 2020 Crown Lands approved a licence application from the council to open the lake to manage flood risk.

DPIE, led by the Environment, Energy and Science (EES) group, is currently working with council to assist them in developing a CZMP for Lake Cathie and Lake Innes and will allow the full range of issues affecting the lakes to be examined, and for consultation to be undertaken with the community to determine the most appropriate management options for the lakes going forward.

Replacing the Kenwood Drive bridge over the lake also remains a priority for council.

Any planned works on the bridge to improve the health of the lake and estuarine environment must align with long-term coastal management strategies in order to be eligible for state government funding assistance for the project.

Testing of a hydro-dynamic model, completed in 2011, will determine the impacts of any potential changes to the lake system as a result of works on the bridge. Those impacts will also determine the most appropriate bridge design and the options available to council before it proceeds with any work. Those results will feed into the CZMP.

Council has confirmed the timeline for its CZMP scoping study is February 2021 and the completion of the hydrodynamic model is likely to be three to four years away if the full suite of background data capture is undertaken.

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