He said there would be some extra pressure on resources, and although water had the capacity for the growth, he would be concerned about the costs of upgrading sewerage infrastructure.
The figures also show that Wairarapa has an ageing population: Masterton's median age will be 47.7 in 2031, Carterton's 51.2, South Wairarapa's 54.3 and Tararua's 42.3.
South Wairarapa has the biggest rise in median age, from 45.3 in 2011 to 54.3 in 2031.
Mr Mark said although he was not worried about Carterton's ageing population, he was concerned about the lack of jobs for young people. "If our ageing population statistics show one thing clearly, it's that our young people are moving out of the district to further their education or take employment in the cities," Mr Mark said.
"It's the sensible thing to do, and one day we'll be the benefactors as they come home to raise their families."
According to the figures, Masterton's population will drop 2.5 per cent from its 2011 figure of 23,500 to 22,900, and South Wairarapa may see a 1.3 per cent decrease to 9300.
Masterton Mayor Garry Daniell said the trends were probably similar to other provincial centres, but did not take into account the potential for growth in industries.
He said forestry, proposed wind farms and the Wairarapa Water Use Project were likely to bring jobs and new business to the district. "I suggest the statistics are quite right if they project current trends, but I think the current trend is not reality," he said.
South Wairarapa Mayor Adrienne Staples said the figures did not come as a surprise and would not have an effect on future planning.
"South Wairarapa went ahead first, so it's no surprise Carterton is likely to have greater growth than us," she said.
Tararua may also have fewer people, with a projected population of 17,100 in 2031, down 4 per cent from 2011.
Wellington's region, including Wairarapa, was projected to grow between 0.1 and 1.0 per cent.
Population in 2031
Carterton up 6.1%
Masterton down 2.5%
South Wairarapa down1.3%
