Key services are lagging behind in Canterbury's Selwyn district as it tries to cope with exponential population growth. 

Stats NZ data shows it remains the fastest growing district in the country, with 3200 new arrivals in the year to June. 

Rolleston and Lincoln experienced the biggest jumps, at 9.6% and 8.1% respectively. 

Massey University sociologist Paul Spoonley told Mike Hosking Selwyn falls behind when it comes to infrastructure. 

For example, he says that of the 20-odd primary schools with more than 700 students, five of them are in Selwyn.  

LISTEN ABOVE