And be warned. Council has reminded residents that any community attempt to open the lake is an offence.

Residents at Lake Cathie have been carefully monitoring the situation over the month as the lake as the water level crept closer to the trigger target.

They have also expressed their ongoing frustration at council and its management of the waterway.

Cr Peter Alley raised the lake opening issue as a matter of urgency at Port Macquarie-Hastings Council's meeting in April and was supported by Mayor Peta Pinson who has been the greatest supporter of a lke opening declaring it a matter of urgency.

Cr Alley said the purpose of raising the matter was to send some words of assurance that Lake Cathie was important to the council and it was a priority.

Council has continued however, to reinforce that any lake opening must be considered against several risk factors. These include weather conditions and tides, low lake water levels which limit the success of an excavated channel remaining open, the likelihood of excessive sand build up in the recently dredged area and potential risk for red weed to enter and become stuck in the lake should it naturally close quickly.

The water level at Lake Cathie reached a maximum of 1.608 metres at 1.45pm on Saturday May 2, and since this time the water level has continued to recede.

As the 1.6 metre trigger point was reached, in accordance with the Lake Cathie Opening Strategy, consideration was given as to whether an opening of the lake was a viable option, council director Melissa Watkins said.

"In the current circumstances council has a management responsibility in terms of flood mitigation particularly in respect of private property and major infrastructure, and an opening will only occur as an emergency response to the likelihood of flooding of vital infrastructure, such as sewer which is essentially the first level of flood impact trigger before flood levels impact private properties," Ms Watkins said.

"Non-vital infrastructure including footpaths and stormwater drains may already be flooded, and we wish to reassure residents that homes are not deemed to be at risk until after vital infrastructure is impacted.

"As the weather forecast shows little chance of significant rainfall within the next week, emergency conditions are not likely to present, and at this time an opening is not recommended. We will continue to monitor the water level, weather forecast and tides on a daily basis, including weekends, to determine if an opening needs to be reconsidered."

Lake Cathie is considered to be an Intermittently Closed and Open Lake and Lagoon (ICOLL) that opens and closes to the ocean naturally in a constant but irregular cycle.

Ms Watkins said ICOLLs are very complex environments, and the impact of artificially opening entrances on fish species and fish habitats is not well understood.

"It is important that management of an ICOLL mimics nature where possible," Ms Watkins said.

"The community should also be aware that undertaking a manual opening themselves is an offence, and previous community attempts to open the lake have been mostly unsuccessful and carry significant risks as safety, environmental and approval protocols are not in place."

Revive Lake Cathie president Danielle Maltman said the decision will be disappointing for many residents who are experiencing direct impacts of the lake's current condition, particulalry along Kenwood Drive.

"Opening the lake is not our first priority but at this stage it's the only action available to save marine life," Ms Maltman said.

Both Revive Lake Cathie and Saving Lake Cathie advocacy groups believe regular grading of the sand berm between the lake and ocean is a better solution as well as addressing the water flow issues at Kenwood Drive bridge.

Saving Lake Cathie spokesperson Stewart Cooper said It is interesting that council has a very exact 1.6m trigger, which is from the now redundant Lake Opening Strategy, but then are "so opaque about their optimum conditions".

"Council has stated that infrastructure that is currently impacted by flooding is not major enough to trigger an opening. Residents who have water in their back yard may dispute councils view on this," Mr Cooper said.

"I would also point out the mosquitoes which are breeding in the stagnant water have reach plague conditions and at least three, that I am aware of, Lake Cathie residents have contracted Ross River in the past month, a known mosquito borne disease. Surely this is a health risk as well."

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