The population of Rangitikei could slump by 40 per cent to under 9000 in little more than a generation, according to Statistics New Zealand.
The projections have been released to Rangitikei District Council to help with its 30-year infrastructure strategy.
In the 2013 Census, Rangitikei had a resident population count of 14,016, though Statistics New Zealand said the "usually resident" count was likely to be 14,500.
But the projections put the district's population at 13,470 by 2021, dropping to 8820 by 2046. The projections were based on 2006 data and will be updated in February next year to reflect the latest Census.
The projections indicate in 2046 Marton would have just 3000 people, down from 4637 in 2001.