At its last ERO review in 2017, Heriot Primary School had 43 children.
This year the roll peaked at 90, principal Colin McHutchon said, and had since settled to 89.
As a result, on Wednesday the Ministry of Education began community consultation on an enrolment scheme for the 143-year-old school.
The ministry said the process was necessary to avoid "overcrowding" at the school, which had capacity for "about 100" pupils.
Mr McHutchon said although he had initially been sceptical about zoning for enrolment, he now believed it might be necessary to address "equity of enrolment" between Heriot and near-neighbour Tapanui School, about 16km away.
"Although we’re happy to be ‘flavour of the month’, in no way would we wish this to be at the expense of a fellow local school.
"It also comes with certain problems of capacity, resourcing and culture management for us, as we’re limited in space, teaching resources and funding due to our size."
Heriot employs about 5 FTE teaching staff. Since the influx, its largest class size has grown to 32.
Mr McHutchon said he was reluctant to speculate on reasons for the sudden influx of pupils from the Tapanui Transport Entitlement Zone.
Transport zoning differs from the proposed enrolment zoning, in that it does not dictate where parents can choose to send their children.
"I think a lot of the influx may be due to our positioning as a ‘rural school’. That’s an idea that sits strongly in some parents’ minds from a perceived values and educational perspective."
The school enjoyed an excellent relationship with Tapanui School, he said.
"I think our similarities [as schools] far outweigh any differences."
Tapanui principal Antony Criglington echoed that sentiment.
The school, which has capacity for about 180 children, has a current roll of 73, down from a peak of 145 in 2017.
Mr Criglington said he believed zoning was necessary to protect both schools.
"At present, there appears to be a perception that children in West Otago will get a better education if they attend Heriot School."
About 25 students from the Tapanui [Transport Entitlement] Zone are attending Heriot at present. About five years ago, the reverse applied, and Tapanui had about 15 out-of-zone students attending from the Heriot zone.
This came down to "parent choice", Mr Criglington said.
"In reality we work closely together and both schools run similar programmes. Our teachers share professional learning opportunities and are on a similar [educational] journey ... It takes a village to raise a child."
Ministry Te Tai Runga (South) leader Nancy Bell said any resulting enrolment scheme would not affect out-of-zone families already attending Heriot.
She said the consultation would end on September 28, after which Heriot School board would be required to implement any decision "as soon as possible".
