Residents of Bluecliffs, where a local state of emergency has been declared due to erosion threatening homes, need to make some tough decisions about their future, Southland District mayor Rob Scott says.
The state of emergency was declared on Thursday morning after heavy rain and sea swell eroded the banks at Bluecliffs township and landfill.
Scott said the declaration meant steps could be taken to open the Waiau River mouth to direct water flow out to the ocean - but that was a short-term fix, aimed at buying time.
In the long term, residents would "need to be having those difficult discussions around managed retreat", he said.
"No-one's ever taken on Mother Nature and won.
"We're kind of having an arm-wrestle with her at the moment. We need to be realistic about what the future holds."
Bluecliffs is a remote settlement about 100km from Invercargill. There are 18 properties, though only six are home to permanent residents, while the rest are holiday homes, or cribs.
Residents had not been told to evacuate on Thursday, but should be ready to do so at short notice if needed, Emergency Management Controller Simon Mapp said.
Two properties were "significantly impacted", but Mapp was unsure exactly how unstable the land was.
Meanwhile, more rain is forecast in Southland on Saturday and a king tide is expected over the weekend, which could worsen the situation.
Scott told Checkpoint the residents, whose homes sat in front of the Waiau River, were getting a "double whammy".
Normally, a sand or gravel bar protected them from the Southern Ocean, with the mouth of the river moving "up and down" the bar over the years.
"When [the mouth is] sitting to the east of the properties, everything's kind of OK. What it's done over the last few months is it's moved itself progressively to the west and ended up right in front of those properties, so you've had the river flowing through, past the land in front of those properties, scouring it out," Scott said.
"It's also taken out the gravel bar, so they're getting attacked from the river and they're getting attacked from the sea as well."
Opening the Waiau River mouth would "take the river out of the equation for doing the damage", he said.
"The sand bar or gravel bar that's normally between the river and the ocean will naturally rebuild itself and provide protection from the ocean as well."
The process was "very complicated and a big job", he said.
"It's important that the residents recognise it's a one-off operation."
Emergency accommodation was in place in nearby Tuatapere for any residents who were concerned or did not feel safe in their homes, he said.
Mapp said Civil Defence was looking at the risks in the area and "what might be possible to provide this community with some more time to manage their retreat".
The opening of the bar would be weighed against the risks.
"This is a highly volatile area and that makes this a very difficult engineering task."
The community landfill was also continuing to erode into the sea.
Southland District Council began work on removing the landfill in 2023, but that work was halted due to reports of explosives buried there.
Further options to manage that risk and remove the landfill were being considered, Civil Defence said.
Mapp said he understood Bluecliffs residents would have concerns and frustrations about the future of their homes.
"We're going to have a chat to them about that and offer some support."