One super city would take over the functions of nine councils in the lower North Island under a draft proposal by the Local Government Commission.
The plan has been described as the most significant reform of a generation, by the commission.
Watch - Wellington Super City: merger proposed
The public was now being called on for submissions, on the new unitary authority, the Greater Wellington Council, with a deadline of March 2, next year.
Under the commission's proposal, the council would take over the functions of the existing nine councils: Masterton District Council; Carterton District Council; South Wairarapa District Council; Upper Hutt City Council; Hutt City Council; Wellington City Council; Porirua City Council; Kapiti Coast District Council, and the Greater Wellington Regional Council.
The new council would have a shared decision-making structure, the commission said.
Power would be shared between the governing body (a mayor and 21 councillors) and 60 members of local boards.
The mayor would be elected by voters of greater Wellington. Councillors and local board members would be elected from eight defined geographic areas, the commission said.
The mayor and councillors would be responsible for high-level decisions affecting all of Wellington.
The local boards would control council budgets and decisions for local matters in established communities. Local boards would be created for Wairarapa; Upper Hutt; Lower Hutt; Kapiti Coast; Porirua-Tawa; Ohariu; Lambton; and Rongotai.
Commission chairman Basil Morrison said the shared decision-making model of a unitary authority with local boards was the best of several options considered by them.
"Local boards ensure the 'local' is preserved in local government," Mr Morrison said.
"They are an integral component of the council structure. Board members would be elected to speak for residents from defined areas and in turn would govern those areas with their own budgets and certain powers.
"We found there were many aspects of local government, which had worked well till now. But we also recognised there are limitations, inadequacies and challenges.
Perhaps most importantly, strong economic and cultural factors inter-connect the region and give it a common future goal. There is a case for change," he said.
"We have proposed a structure of local government to best meet the needs of the people of the entire region over the next 30 years.
"This proposal offers the greatest opportunity to address the significant future issues facing the region. Wellington must address challenges of investment in infrastructure, changing demographics, the need for economic development, and management of the impact of natural hazards and climate change."
These issues were regional in scale and required regional responses, Mr Morrison said.
Some of the key proposals
* the elected members of Greater Wellington Council would be: one mayor, 21 councillors and 60 local board members;
* the administrative headquarters of Greater Wellington Council would be in Wellington City but council services would also be provided at area offices;
* local boards would have responsibility for decisions about local council functions unless there is a good reason for those decisions to be made at a regional level;
* local boards would have powers and budgets for local facilities;
* decisions about how to handle the transition to a single rating system would be left to the new council;
* two formal structures would ensure Maori participation in decision making - a Maori Board and a Natural Resources Management Committee;
* a proposal for a stand-alone Wairarapa council has failed to meet required tests, as the Commission was not satisfied it would have the resources to effectively carry out all local government functions in the future;
* the first elections for the new council could occur in October 2016 if the draft proposal proceeds through all its next steps, which could include a public poll; and
* public submissions on the proposal close on March 2, next year.
Politicians' tweets break embargo
Labour MP Chris Hipkins and Hutt City councillor Campbell Barry revealed details ahead of an announcement by the Local Government Commission.
Mr Barry said the proposed format would see one Wellington council made up of eight local boards. It would be called the Greater Wellington Council and would have one mayor, 20 councillors and 60 members.
"No surprises. They haven't listened to the people... The Local Govt Commission have completely ignored the overwhelming feedback from Hutt Valley residents opposing a Wellington Super City," Mr Barry said.
Mr Hipkins tweeted: "No wonder Local Govt Commission delayed super city announcement till after election. They're proposing to ram it through before next one."
He also revealed that Upper Hutt would only have two councillors on the council of 21, under the proposal.
"Hutt Valley people MUST be given the chance to veto the super city takeover by way of a referendum!!", he tweeted.
He called the commission's process a "wasted opportunity" because it would not garner public support.
Mr Barry urged the public to have their say in submissions, which would be open until March 2, next year.