The Waitaki District Council this week decided to move ahead with a public notification to reclassify a section of the park's western edge so the organisation could go ahead with its plans.
But after a presentation led by St John Rural Otago territory manager James Stewart and Christchurch architect Nate Harrold several councillors voiced their displeasure with the decision before the council vote.
Crs Colin Wollstein, Guy Percival, and Jan Wheeler voted against the motion.
Cr Bill Kingan, who did not vote against the move, asked whether St John was prepared for any adverse reaction from the community "because I think there will be".
"It takes years and years to grow a tree, it takes a minute to cut it down," he said.
The proposed 4000sqm footprint was "quite a chunk".
Cr Wheeler said a St John station in that stretch of Wansbeck St could create "chaos" on an already busy stretch of State Highway 1 and could be perceived as the start of a slippery slope with respect to parks.
"These parks are really precious to Oamaru," Cr Wheeler said.
"They were put there for a reason.
"I think the community would support you [St John] going elsewhere."
Cr Wollstein said he believed there could be a "huge public backlash".
He asked why St John had not proceeded with a possible Saleyards Rd area site.
He also said the organisation should take on the public consultation itself.
Mr Stewart explained how the organisation used "heat maps", to show where ambulance callouts were highest, to help it decide on a suitable location.
There were space requirements for staff and vehicle access issues at other sites St John had looked at.
Disruption to the residential neighbourhood around the park would be "minimal and understandable" - on average residents could expect one-and-a-half responses with lights and sirens every 24 hours.
Cr Melanie Tavendale said at this stage of the process the council was not "taking a stance per se" on the proposed development.
"I think we need to go out and test the waters."
Cr Jim Hopkins said the importance of the operation should be taken into account.
If a commercial business approached the council with the same site proposal "council would have said, `No, go away'," he said.
Waitaki Mayor Gary Kircher said St John had been through a "long process already".
If, as some suggested, it bought a site and demolished a building, it could add up to $1.5million to the project.
St John had built up a lot of goodwill in the community by saving lives and there would be further checks through the process.
