The NSW Planning Department's local area population projections, released last week, estimate the population of The Hills will grow by about 1.3per cent every five years between next year and 2036. That would take a population of 177,200 to a population of about 259,000, a total increase of about 57per cent.

Most of that growth is forecast for the northern division the largest area with the population there expected to grow 120per cent, compared to increases of just 30per cent and 20per cent in smaller central and southern divisions which are already heavily developed.

In Blacktown LGA growth of about 2per cent every five years is expected with a jump from 300,000 people in 2011 to about 480,000 in 2036. By far most of that growth will be in the northern half of the area, which is expected to grow by 175per cent.

The south-west generally is expected to be the fastest-growing sub-region in Sydney, leading both Sydney City (an estimated 60per cent increase) and the north-west (52per cent).

The figures also show while there will be an increase in the percentage of people aged 65 and above in all local areas in NSW, growth in the 0-to-age14 population will be limited mostly to the metropolitan and coastal regions and the areas surrounding Canberra.

In the Baulkham Hills LGA about 10per cent of the population is now aged 65 or over but that figure is forecast to rise to about 15per cent by 2036.

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