He said such a major regionwide change could create a leadership vacuum.
All-new mayors and newly elected councils would be focused on getting up and running after the next elections, attention turning away from critical major central government changes altering how local government operated.
What was happening in Northland was important locally and to New Zealand's wider democracy.
"I have not heard of this happening before," Asquith said.
He said a perfect storm of change events was compounding normal leadership churn.
This included the central government interventions of Three Waters, Local Government Reform and Resource Management Act change.
"It's not evolution, it's revolution," Asquith said.
He said the price being paid by local government for the way central government was bringing in Three Waters change had become too high.
Asquith said, with the end of district health boards, local government was critically important as the last remaining option for decentralised democracy in an increasingly
centralised political system.
New Māori wards are among other major Northland local government change. Nine of the region's 44 elected councillors will come from four new Māori wards.
The winds of leadership change are also playing out across Northland council chief executives. The Northland Regional Council's Jonathan Gibbard starts in October. The Whangarei District Council's Simon Weston has been in the role a month. The Far North District Council's Blair King has been in his role three months.
The Kaipara District Council's chief executive of four years, Louise Miller, will become the region's longest-serving council chief executive.
Smith said his change decision finally came this week as the Government introduced the new Water Service Entities Bill to Parliament. This legislation underpins establishment of New Zealand's four new inter-regional water services entities.
He said New Zealand was now at a critical point in its constitution. Three Waters was moving away from the Te Tiriti o Waitangi principles of ngā tāngata katoa or all people.
He said the bill showed it was clear the Government had paid no attention to the voices of its people, including the alternative Three Waters option put forward by Communities for Local Democracy, a breakaway group of 31 of New Zealand's 67 councils representing 1.5 million people.
Smith's move means there are now five would-be National Northland electorate candidates, including Far North District Councillor Felicity Foy.
The Northland Regional Council chairwoman, Penny Smart, is standing again, as a councillor. Incoming NRC councillors select their leader after the election.
She said Northland's across-the-board mayoral change was coincidental. There were plenty of good people in Northland who would take up the mantle and do a good job.
Smart said potential candidates needed to make sure they knew what was going on in local government.
"They really need to do their due diligence. There's a lot going on all at once. I would hope they are as fully informed as possible before they take up office," Smart said.
■ Local Democracy Reporting is Public Interest Journalism funded through NZ On Air.
