Recent rain overnight on April 27, according to Manly Hydraulics Laboratory data, increased the lake height between 5am and 7am from 1.536m to 1.553m.

This data is collected under the NSW Coastal Data Network Program managed by Climate Change and Sustainability Division, NSW Department of Planning, Industry and Environment.

The Lake Cathie Opening Strategy outlines the lake is only to be opened when the lake water level is at, or exceeds, 1.6m or falls below 0.2 metres with high salinity, if optimal conditions allow.

A statement from council earlier this month (April) said they were monitoring the water levels twice a day

"Should the 1.6m trigger be reached, a decision will be made which will also consider the optimum opening conditions - including forecast rainfall and water level continuing to rise, as well as tidal conditions," a spokesperson said.

"Should council determine to open the lake, the community will be notified immediately and we will then proceed to engage contractors to undertake the work.

"We want to assure the community that we are monitoring this closely and we have mechanisms in place to open the lake in the case of an emergency or where water levels reach 1.6m and meet optimum opening conditions."

These conditions include:

"We are aware that the Aqua Crescent reserve footpath is currently inaccessible due to inundation of water over the path. As such, we ask that community members avoid the area while the path is underwater."

Council last artificially opened Lake Cathie to the ocean on July 11 in 2018 after residents expressed their concerns about the water level impact on surrounding properties.

In February, 2019 the lake again reached the high salinity trigger point for an opening. However at the time, council director Melissa Watkins said it would not artificially open the lake to the ocean, due to several risks associated with the action.

At the November 2019 council meeting, council voted in favour of obtaining a one-off licence from Crown Lands to open the lake.

However, 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.

The lake briefly opened to the ocean on January 14 as a result of a significant high tide and large swell.

Heavy rain at the end of March this year, has also caused low-lying inundation in some areas and shifted the salinity of the lake to zero.

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