A local state of emergency has been declared for the remote Southland community because the high-flowing river and sea swells were undermining the land.
The community lost about three metres of land in a day this week as the river claimed gravel, sand and bank.
Three-metre king tides and more rain is forecast over the weekend and residents have been told to prepare to evacuate at short notice if needed.
Accommodation has been offered to residents who want or need to leave, with officials confirming at least one person has taken up the offer.
Bluecliffs resident Rex Rowe said it had been a stressful and nervous time for many residents.
"Not all areas down the back have been affected. But what has, has been massive and very, very quickly - eight to 10 metres in sometimes three to four days."
He was glad that the weekend's forecast did not include a large southerly swell hitting the coastline, which would add force behind the king tides.
"I'm quietly confident myself that we will not suffer too much damage with these king tides."
It was the peace and tranquillity that attracted him to the area, but erosion in the last year or so has caused anxiety for many in the community.
It took a toll when you realised more land was gone but he has been grateful for the support that has been offered from local councils, he said.
"There's a lot of hurdles to be jumped to actually do anything on the river or sea shore. At the beginning, I would never have expected that," Rowe said.
That changed once he started to work more with the local and regional councils.
He expected cribbies and residents alike would be thankful once the river mouth was opened at a different location, which Environment Southland was working towards next week.
On Friday, Southland District Council building inspectors were assessing homes and giving residents notice if there were any issues.
Emergency Management Southland group controller Simon Mapp confirmed no homes were deemed unsafe to live in.
He expected there might be some more erosion over the weekend but not enough to threaten any of the houses.
"It's constantly eroding and when you have high rain flows in Fiordland - [which impacts] Lake Te Anau and Lake Manapōuri - that impacts the Waiau River coming through. We're due for some more rain over the weekend so we're just keeping a watching brief," Mapp said.
He could not give a date for when work to create a new river mouth entrance would start, saying it was a volatile environment and dangerous work that needed ideal conditions and the right plan in place to go ahead.
He asked people driving to Bluecliffs to look at the erosion to stay away, saying it was volatile area and more traffic was not helping the situation.
That was when it became apparent there could be a problem for the community if the river mouth moved.
"The mouth moved up unfortunately and we had a massive storm late last year and that really shook the cage here."
Standing on the deck behind his house, he remembered watching the mouth blow out closer to the properties one afternoon.
"It was a natural event, it wasn't assisted by any machines. To ... watch how quickly it just removed that gravel bar and from then it's moved down slowly. But it's narrowed up."
But recent heavy rain and full lakes meant it was having another go at the community, he said.
Other residents have raised concerns that the hydro lakes upstream in Fiordland were limiting the amount of water coming downstream and forcing the river to divert past Bluecliffs instead of punching directly through the gravel bar.
Meridian Energy development general manager Guy Waipara said the Manapōuri Power Station has been operating under strict resource management consents for decades.
"These include a requirement that we maintain a longstanding monitoring programme, and this confirms that the risks posed to these homes is a result of the sort of coastal erosion we're seeing in other parts of the country, not the operation of the Manapōuri Power Station," Waipara said.
"Specifically, our monitoring shows the beach barrier and changes adjacent to Bluecliffs Beach Road are consistent with a high energy coastal environment that's subject to strong, tidal currents and the prevailing winds of Foveaux Strait.
"The ongoing impact of climate change will mean more examples like this around the country, which is why it's critical we continue to decarbonise by increasing the amount of renewable energy we use within Aotearoa and globally."
He acknowledged it was a distressing time for the community regardless of the cause of the erosion.
Meridian Energy was working to support local authorities to find a solution.
"Any works they undertake at the mouth of the river will require us to manage flows to ensure these works are completed safely and effectively."