Despite all of the new employment opportunities coming to Southland, Infometrics predicts a slowing down of population growth in the south.
Infometrics principal economist Nick Brunsdon delivered a presentation to the Risk and Assurance Committee on Long Term Plan assumptions.
But Invercargill Mayor Tom Campbell didn't want to accept it, saying the growth assumptions were too conservative.
Nick said the Southland population grew 0.7% over the past decade and is only expected to increase 0.3% over the next 10 years - compared to 0.7% nationally.
"This might seem low but employment impact is gradual," he said.
He said New Zealand's population overall was slowing down and by mid 2040s to 2050s, the population growth will be zero - similar to China and Eastern Europe.
"There is a slow down and it's not a 'picking on Invercargill thing,'" he confirmed.
Nick talked about the impact on population growth from employment across industries aquaculture (893), Datagrid (80 and then 447 once operating), Aspiring Metals (86), and wind farms (445).
"There is a lot going on. It's a pretty exciting time for Southland."
But he said New Zealand has a tight labour market in an aging population and there are limitations.
The slowing down will induce quite a constraint on population growth regionally, but international migration will be a key part of the puzzle, he said.
Mayor Tom Campbell backed up what Nick said about there being a lot going on the city, "there is a very optimistic vibe in the city based on growth."
But he was surprised about the predictions and said he was unwilling to support the figures, especially with strong employment forecast.
Nick predicts Invercargill will only grow from 58,000 to 59,900 over the next 10 years, and eventually will hit 65,600 by 2057.
"It's quite a sustained population growth, but it's not particularly strong."
Mayor Tom said they should assume the past informs the future, "so we should assume the last 10 years is going to be like the next 10 years."
Nick said he acknowledged there was a huge amount going on with projects, "and there is a cause for optimism in that."
But he confirmed New Zealand's population growth is expected to half over the next 10 years.
"It is a demographic reality."
The committee instructed staff to take away the assumptions from Infometrics and consider them and bring them back in October, before they make a recommendation to council.