A greenfield site on which a large housing estate was proposed would be protected as open space under the new Area Plan.
The proposed £40m Sulby Riverside development was rejected by the planning committee last month, despite being recommended for approval.
Blythe Church Investments Holdings Ltd had sought detailed planning approval (22/00679/B) for the first phase of the scheme which could see a total of 66 houses and 12 flats built on fields at Poyll Dooey.
Its application also sought consent for a second phase of up to 127 more homes, making 205 in total.
But the planning committee voted three to two against the scheme, amid concerns over flood risk and possible loss of two red-listed wildflowers.
The applicants have since lodged an appeal.
The site borders a nature reserve and a protected saltmarsh. It was announced last week that a public inquiry will be held into the draft Area Plan for the North and West.
Public inquiry papers were also published setting out the proposals including the addition of new development sites.
But there are no plans to zone Poyll Dooey for housing. Instead, it is designated as ‘open space’.
It had been considered for housing as development site RR004 but this was rejected.
Recommending approval for the Sulby Riverside scheme, planning officer Hamish Laird said the draft Area Plan should not be taken into account as it was not yet in place.
He said the site is designated in the current Ramsey local plan for light industrial use and some residential at its eastern end.
‘No further work has been carried out on the Draft Area Plan since publication and given that the proposed policies and allocations contained therein have not been the subject of public scrutiny, it is effectively for information only, and as a consequence, holds no weight,’ the planning officer said.
A government spokesman said: ‘All of the sites that were submitted to Cabinet Office for consideration - for whatever purpose - were given a site code.
‘The site at Poyll Dooey was given the site code RR004 and was assessed via an assessment report.
‘The draft Area Plan for the North and West did not support Poyll Dooey as a potential development site for housing and instead proposed the site for open space or for a particular purpose.
‘In the papers published last week, the Cabinet Office has not changed its stance and the site remains unsuitable for residential development. This was reflected in an updated map 4 for public inquiry purposes which was published on March 22.’
Among the objectors to the Sulby Riverside scheme was the government’s flood management division which said no homes should be built on a floodplain.
And Manx Wildlife Trust said it would make a mockery of the island’s Biosphere status.
Applicants Blythe Church Investments had proposed a Spine Road as part of the scheme that would double as a flood barrier.
Planning officer Mr Laird said the site should be flood-free even in the event of a once in 200-year flooding event of 6.05m.