The Cabinet considered leaving the northernmost part of Rodney, north of Dome Valley and Omaha forest, out of the Auckland Super City, official papers show.

Instead, the Cabinet opted on August 3 to take Auckland's coastal playground from Waiwera north out of the Super City.

Cabinet papers released to the Herald under the Official Information Act show the Cabinet was influenced by vocal opposition in Rodney to being part of an urban-dominated Super City.

Local Government Minister Rodney Hide, the ministries for the environment, economic development and transport, plus the agency designing the Super City, all supported keeping Rodney District Council in the Super City.

Mr Hide said Auckland needed a governance system that was not compromised by parochial interests.

It was in the long-term interests of Auckland for all of Rodney and the northern part of Franklin District to be part of the Super City.

But this view on the northern boundary and the argument by the Ministry for the Environment that northern Rodney contained coastal areas of regional and national importance that Aucklanders had invested heavily in protecting lost the day in Cabinet.

The Cabinet decision was "primarily a response to vocal opposition to inclusion in Auckland from the [Rodney] district".

Of the 164 submissions to a select committee on Auckland governance that raised the subject, about 40 per cent wanted all of Rodney to be excluded from the Super City, and about the same percentage wanted some of the northern, more rural part, of the district excluded.

Only a small number wanted all of Rodney to stay in Auckland, the Cabinet was told.

After news of the split was revealed by the Auckland Regional Council and led to frantic lobbying, the Cabinet did an about-face on September 14 and put all of Rodney back in Auckland.

"There is as much opposition to boundaries that split communities within Rodney District as there is to the inclusion of the district within Auckland," the September 14 Cabinet paper said.

The paper, written by Mr Hide, said alternative approaches to splitting Rodney had been suggested but they could engender fresh opposition from other affected interests and "be damaging to the credibility of the Auckland governance reform process".

One option was to split the northernmost area of Rodney, north of the Dome Valley and Omaha forest, that was "clearly rural and somewhat isolated by geography and distance from metropolitan Auckland".