The Clifton and Waitara community boards appealed against the proposed re-shuffle to the Local Government Commission.
Although all voters would also have five votes for at large councillors, the Waitara Community Board chair Jonathan Marshall told the commissioners the North ward's voice would be eroded.
"We support the retention of the two North ward councillors for fair and effective representation," Marshall said.
He said a single councillor could not cover the diverse communities of the district's largest ward.
"It is almost impossible for two councillors to visit each and represent each of our communities to the council, let alone if we were reduced to one councillor."
Marshall said the North ward should keep its two councillors, taking one from either the five at large seats or the city ward's six seats.
He said council arguments that five at large councillors would mean better representation for North ward was not realistic.
"We are 28 months into our current term and most councillors of the NPDC have not set foot in our communities in an official capacity."
Clifton Community Board member Murray Seamark also didn't think "any at large elected member would have the same passion and fortitude, given that it remains most likely they would not be a North ward resident".
Seamark said a suggestion that the new Māori ward councillor would help represent the North ward was unrealistic.
"That person's going to be extremely busy and … will probably sit at a higher level, ensuring that all Māori voice is heard throughout council processes, as opposed to getting down to what's happening to a stormwater drain in Waitara."
Seamark understood at large councillors would give more choice to Māori roll voters, "but my point is it doesn't need to be five representatives, especially when it comes at the expense of other minority communities".
He said the council's own social inequalities data showed the need for North ward's dedicated representation.
"The lowest people of working age, highest rate of Māori identification, highest level of activity limitation, lowest home ownership rate, and the lowest median income.
"The bottom line is North ward, in comparing all other district wards, is the largest, is the most diverse and has the highest needs.
"Electing candidates is only a small part of representation; representation really happens post-election when you have access to your representative."
Mayor Neil Holdem told the commissioners that introducing a single-seat Māori ward raised problems of fairness.
"Those on the Māori roll would only get one vote, and a legitimate concern was raised about basically marginalising their voting power.
"This model we believe better represents views of communities while also solving what were some of the major criticisms of bringing in a Māori ward."
NPDC governance lead Julie Straka said the proposed mixture of wards and at large councillors allowed more influence for Māori roll voters and those in the non-city wards, under the STV voting system.
"Under STV it's about influencing who sits around that table. So, while we talk about how many votes you get, under STV you get to prioritise any number of votes for the candidates standing.
"Going to the mixed model allows those wards that have a lower number of direct representatives … to have greater influence around the table by having the at large component."
The Local Government Commissioners will now deliberate on the appeal and must announce their decision before April 10.
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