The Baird government has created 19 new councils across Sydney and NSW. And the government has said it would merge another nine, pending the outcome of litigation over council mergers.

"The most comprehensive local government reform in more than 100 years will result in 19 new councils beginning operations from today," Premier Mike Baird said.

Administrators and interim general managers have been appointed to each of the new councils, which will not hold their elections until September next year - 12 months later than those not being merged.

Local Government Minister Paul Toole said it would be business as usual for residents in new council areas, with services operating as normal.

But sacked mayors and councillors said leaving councils under the control of an administrator and general manager for more than a year was "undemocratic".

And Opposition leader Luke Foley promised that if elected in 2019 his party would create a "process for de-merging" councils that had been forced to amalgamate.

"We will allow local communities to determine their futures democratically," Mr Foley said.

The Baird government's announcement on Thursday also revealed it had shied away from merging a number of politically contentious regions.

Deputy Prime Minister Barnaby Joyce, facing a tough fight for the seat of New England, had argued against a proposed merger of Tamworth and Walcha councils.

Those councils will be spared amalgamation. Also spared amalgamation are Hawkesbury and The Hills shire council in north-west Sydney, and Kiama and Shoalhaven council. Delegates appointed by the government to assess those mergers advised against them.

The Deputy Premier, Nationals MP Troy Grant said he had spoken to Mr Joyce about the proposed Tamworth and Walcha merger "on two occasions" but denied he had done the deputy prime minister a favour.

"He just outlined his concerns in relation to Walcha being part of the merger process," Mr Grant said. "This happened well after I had already attended Walcha and sat down with the Walcha Council and formed my own views."

Nine mergers, including the proposed amalgamation of Botany and Rockdale, have also been postponed while legal action is underway.

Mr Baird said he could not control the outcome of those challenges.

"There's a group of councils that seem to be determined to hang on to head office costs, hang on to more councils, rather than say to their community... I think you would want more childcare, you want more community transport, you want better sporting facilities."

The Premier described the four-year process leading to the creation of new councils as "long as well as painful at times" but one that had involved a lot of consultation.

"Ultimately what we have to do is make a decision," Mr Baird said. "And today is that day," he said.

"I strongly believe the people have us here to make decisions. Now we think this is in the long-term interests of every rate-payer in this state."

Each new council will receive up to $10 million to meet the costs of merging, plus up to $15 million for investment in new community infrastructure.

However the process of establishing new councils remains unclear. The administrators appointed to run the new organisations will appoint "Implementation Advisory Groups" made up of former mayors and councillors.

"Any councillor or any mayor that wants to participate in this, and I don't care about their political badge, anyone that wants to play a constructive role in this, they can," Mr Baird said.

Mr Toole said "inductions" would take place over the weekend with administrators and newly appointed interim general managers. Mr Toole said the administrators would "take on the functions" of previous mayors and councillors, though there would be some limit to this.

"The administrator cannot go out to councils and change local environmental plans," Mr Toole said. "If they are to be looked at differently they must go to a planning authority."

Outgoing Leichhardt mayor Darcy Byrne said: "Winter has come to the inner west and like Ned Stark the heads of democratically elected representatives have been chopped off.

"If Mike Baird and Paul Toole think that by arrogantly imposing their will on the inner west that the have finished this fight, they have got another thing coming," Mr Byrne said.

A review of the merged councils would be conducted in four years.

As part of the reforms, Mr Baird also revealed new rules to curb the influence of property developers on councils.

New councils:

Armidale Regional Council (Armidale, Dumaresq and Guyra)

Canterbury-Bankstown Council (Bankstown and Canterbury)

Central Coast Council (Gosford and Wyong)

City of Parramatta Council (Parramatta and part of Hills, Auburn, Holroyd and Hornsby)

Cumberland Council (Auburn and Holroyd)

Edward River Council (Conargo and Deniliquin)

Federation Council (Corowa and Urana)

Georges River Council (Hurstville and Kogarah)

Gundagai Council (Cootamundra and Gundagai)

Snowy Monaro Regional Council (Bombala, Cooma Monaro and Snowy River)

Hilltops Council (Boorowa, Harden and Young)

Inner West Council (Ashfield, Leichhardt and Marrickville)

Mid-Coast Council (Gloucester, Great Lakes and Greater Taree)

Murray River Council (Murray and Wakool)

Murrumbidgee Council (Jerilderie and Murrumbidgee)

Northern Beaches Council (Manly, Pittwater and Warringah)

Queanbeyan-Palerange Regional Council (Queanbeyan and Palerang)

Snowy Valleys Council (Tumut and Tumbarumba)

Western Plains Regional Council (Dubbo and Wellington)

Subject to the decisions of the courts, the Minister has announced his in-principle support for the following mergers:

Botany and Rockdale

Randwick, Waverley and Woollahra

Bathurst and Oberon

Ku-ring-gai and Hornsby

Mosman, North Sydney and Willoughby

Blayney, Cabonne and Orange

Hunters Hill, Lane Cove and Ryde

Burwood, Canada Bay and Strathfield

Shellharbour and Wollongong

Merger proposals pending:

Newcastle and Port Stephens

Dungog and Maitland

Armidale-Dumaresq, Guyra, Walcha and Uralla