The state of emergency will remain in place for a week in those districts, but will be lifted elsewhere across the region.
This comes after intense rain earlier this week that caused chaos, including forcing many people to evacuate and badly damaging roads.
Ashburton Mayor Neil Brown told RNZ's Morning Report programme today that farmers were trying remediate their land, stock and fences.
"Our local road network, we've had a good view of it now and places of it are severely damaged. It's going to take a wee bit of time to get that up and running again - that's our focus now ... and also looking out for the welfare of our people."
Brown said the longer state of emergency meant they would have the reassurance to keep moving in the recovery phase.
Selwyn Mayor Sam Broughton agreed, saying they had more authority under a state of emergency.
"If you needed extra powers you might have to go back to the minister on a case-by-case basis to request the powers for particular actions. This way it just means recovery managers can get on with things rather than needing to re-negotiate with Wellington," Broughton told Morning Report.
In particular, he said some road repairs may require those powers.
"It will rain again this winter and we don't want to have another situation like this that could have been avoided if we'd got on and rebuilt stopbanks and done other work."
Those in rural areas, like Springfield, were particularly badly hit than metropolitan places, he said.
"A flyover yesterday showed there was a lot of fields where water has come on to those fields and caused a lot of problems.
"There's thousands and thousands of dollars of work to bring farms back to where they were and winter feed will be short for some farmers because it has just been washed away.
"So the stresses of last weekend were immediate for some and will certainly be ongoing for many in our community in the coming months."
"We've got 27 rapid assessments being undertaken and that's from anything, welfare to buildings ... and that's to ensure that we're connected to what's happening on those particular properties and the support that we need to wrap around those people," Gordon told Morning Report.
"But really getting all the emergency work done as soon as possible is a priority for us."
Support for farmers
Brown said insurance assessors were in to look at the properties of people who became displaced due to flood damage. Those displaced still had another place to take shelter, he said.
Farmers were in need of assistance with clean-ups, he said, and there had been offers of help. He encouraged those wanting to volunteer to submit their interest via Federated Farmers.
Selwyn also had some displaced people but were being accommodated.
"I think it's really hard to ask for help for some people and often it's been neighbours requesting that you know, perhaps we should check on someone that they've seen that might need a bit of extra assistance," Broughton said.
"I'd just say if you're still feeling like the effects of the flood are immediate for you and you haven't had the support that you think you need, please reach out, call 0800 SELWYN and connect with the team who want to help and working across agencies."
"Our community is one that really does care," Gordon said.
"I've come to see the great community spirit come out through this and other emergency events we've had, so reach out if you need support."
Federated Farmers South Canterbury president Greg Anderson told Morning Report heavy machinery and diggers were needed to create channels for the rivers to return to their normal courses.
Anderson said local authorities were looking at ways to divert rivers and clear the water off farmers' land.
Volunteers and the community had offered help to struggling farmers, he said.
