Invercargill could be home to 61,300 people by 2037 if major Southland projects deliver the jobs and migration their backers promise, according to forecasts the city council is being asked to build its next 10-year budget on.

A report to Tuesday's council meeting asked councillors to choose between two growth scenarios for the 2027–2037 long-term plan: a medium case of 0.3 per cent a year population and household growth, or a high case of 0.5 per cent population growth and 0.4 per cent household growth. Staff had already written the draft assumptions around the more optimistic option.

The forecasts were prepared by economic consultancy Infometrics and build on regional work done with Great South. They assume aquaculture expansion, the Datagrid data centre at Makarewa, the Aspiring Materials project and wind farm developments all proceed, lifting employment and drawing in migrants, particularly in the late 2020s.

What the numbers say

Under the high scenario, employment in Invercargill grows 0.7 per cent a year to 33,900 filled jobs by 2037, with the strongest growth late this decade as construction of Datagrid and the wind farms peaks. That is still behind the forecast national rate of 1.1 per cent.

The population would rise 0.5 per cent a year to 61,300 by 2037 and 68,000 by 2057, and the number of households from 23,600 last year to 24,800 by 2037. The city keeps ageing: residents aged 65 and over would make up 20 per cent of the population by 2037, while the share of children under 15 falls.

Infometrics also expects international student enrolments in Southland, still well below pre-pandemic levels, to grow about 9.5 per cent a year and recover fully by 2037.

Housing remains cheaper than the national average, with a house-value-to-income ratio of 3.9 against 5.9 nationally. Renting is a different story: rents have climbed from 14 per cent of mean household income in 2005 to 18 per cent this year, eroding the city's affordability edge.

The trade-off

The report is frank about the risk. The high scenario assumes a high degree of regional coordination so that big projects are staged rather than competing for the same construction workers. If they do compete, more of the work could go to crews brought in from outside the region, with little lasting impact on the local population.

Choosing the optimistic path gives the council more room within the rates capping window, but if growth falls short, revenue would miss forecasts and the squeeze would come in later years. The medium scenario means tighter rates planning but less risk of missing revenue targets.

Staff also proposed a 0.7 per cent annual growth in rating units, pointing to post-Covid growth of up to 3 per cent a year in commercial and industrial properties after a decade from 2012 in which rating unit numbers barely moved.

Whatever councillors decided on Tuesday, the assumptions will be refined through budgeting, stress-tested against higher and lower growth, and brought back to the council in December before audit in January. The report warns that an optimistic choice could draw an emphasis of matter in the audit opinion. Public consultation on the long-term plan is scheduled for March and April next year, with adoption due in June 2027.