Outraged Central Coast residents took to social media to vent their outrage as the lakes system failed to cope with extraordinary rain over the weekend, after years of inaction to address rapid development around Tuggerah Lakes that caused unprecedented flooding this week.

"The questions we need to ask, and get answered, is why has this happened and what do we need to do to make sure it doesn't happen again in future," said Central Coast councillor and former Gosford MP Chris Holstein, who acknowledged some of the outrage flowed from the absence of public acknowledgment of the severity of the flooding and impact on people.

The former deputy chair of the NSW Flood Mitigation Authority, who entered politics in 1989 after successfully campaigning for the NSW Government to help buy flood-prone houses at Narara, said authorities needed to address people's short term needs, but the council needed to lead the campaign for long-term work to address the lakes' flood issues.

These include raising houses in some low-lying areas, investigating whether a channel should be established in the northern part of the lakes system, the use of dredges to prevent the build-up of sand near the channel opening to the ocean at The Entrance, the impact of a recently-built rock groyne, and a possible breakwall.

Mr Holstein warned that any action needed to be underpinned by solid evidence, and the council could not deal with the many issues on its own.

"What I do know is that you can't compare catchments. What has to happen is a full assessment of what work has been done in the past, what reports are already available to us, whether we can re-instigate the findings of those reports and what other things need to be looked at," Mr Holstein said.

At a council meeting on Wednesday night he asked for a 2014 report commissioned by Wyong Shire Council to be made public. The report is believed to have costed a breakwall at The Entrance at $50 million. Mr Holstein said the council could not fund the project and he had reservations about the proposal.

"There's been a lot of talk about this report and the breakwall, but I haven't seen it. No one seems to have seen it. As a starting point we need to look at all the information we have available because no one thing is going to sort this out," Mr Holstein said.

Wyong MP David Harris said the lack of information and support for thousands of people trapped in their homes by rising flood water, many without electricity, was one of the biggest issues as flood water continued to rise on Monday and Tuesday because of runoff and the failure of the single channel at The Entrance to release the water to the ocean.

On Tuesday Mr Harris asked Premier Gladys Berejiklian to declare a natural disaster to assist property owners with insurance and mobilise support for flood-affected people and businesses.

"It is a disaster, that's clear. Main roads have been cut for days because of the level of water across them so there's been traffic chaos. Schools have been shut. Many people have not had power since Friday and the level of response has been slow and inadequate," Mr Harris said.

On Monday Mr Harris wrote to Emergency Services Minister David Elliott about the findings and recommendations of an investigation by Brigadier Darren Naumann after Wyong suffered severe flooding in 2015.

"I've not seen the results of that investigation. I was with Brigadier Naumann when he spoke with people at Chittaway, which has been severely flooded again. These natural events happen, but we don't seem to act on what we learn," Mr Harris said.

He had spoken with people about a northern lakes channel to reduce the pressure on The Entrance channel and said it was one proposal that could be investigated.

"Even though the water was heading out to sea we had particular problems this time because of where the really heavy rain fell, in the catchment area rather than just along the coast," Mr Harris said.

One rain gauge at Hamlyn Terrace, north of Wyong, registered 900mm in three days.

"Rain fell in the catchment area and there was significant runoff into Wyong River and Wallarah Creek which found its way to the lakes, and explains why the flooding got worse for several days after the rain stopped," Mr Harris said.

Central Coast mayor Lisa Matthews welcomed the natural disaster declaration on Wednesday which will help affected residents get assistance and support, and government funding to help Central Coast Council repair infrastructure.

Cr Matthews repeated her call for Premier Gladys Berejiklian to visit the region and see firsthand the impact the disaster had on the Central Coast community.

"It is fantastic to see the NSW Government step in and give council and the community the support we need to recover and I look forward to welcoming the Premier to our region," Cr Matthews said.

"I want to show the Premier the impact of the recent event and ask for her support to find a long-term solution to the maintenance and viability of our waterways. This is not the time for political point scoring and finger pointing.

"We must pull together. All levels of government must work hand in hand with our community in the recovery and the long-term future of the Central Coast."

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