"It's well past its use-by date. The firefighter's role has changed dramatically from 40 years ago, from predominantly just fighting fires to doing all of the other emergencies and [activities] that are required."
Whanganui Fire Station attended 706 real incidents in the 2016 financial year. Just over half - 361 - were for actual fires, while 282 were for rescue, emergency, medical or hazardous emergencies, and 53 were special service calls.
It also attended 302 false alarms.
Mr Baxter said the act would give the new organisation the funding and legal authorisation to do what the fire service has been tasked with previously.
"In a lot of respects, the changes to the legislation are catching up with the demands and needs of the community by providing an updated mandate," Mr Baxter said.
Mr Baxter said the transition, which was progressing through Parliament, had been hailed by the majority of those in the affected organisations, but has a few kinks to be ironed out.
He said the transition was a big task, especially with the usual day-to-day incidents still to attend.
"It's a very important aspect of our organisation to make sure our business as usual emergency responses continue uninterrupted. The truck keeps going down the road while we're trying to change the tyre basically."
Internal Affairs Minister Peter Dunne said the funding for the transition and the organisation's new responsibilities would come from an increase to the fire levy, which was paid on insurance for contents, property and motor vehicles.
The levy will be extended to also include third party motor vehicle insurance.