Southland District Mayor Rob Scott has declared a local state of emergency for the Bluecliffs area.
It comes as a "precautionary measure" to ensure Emergency Management Southland is able to respond to threats to life and property from erosion and the landfill at Bluecliffs.
In a statement from Civil Defence controller Simon Mapp on Thursday, he said heavy rain and sea swells are to blame for the increased erosion.
Mapp said as a result, homes in the area have been put at risk.
Although local residents aren't required to evacuate, they have been warned to prepare and be watchful for the situation, in case they need to leave at "short notice".
"Declaring this local emergency means we're able to take steps for a physical opening of the bar at the Waiau River mouth to manage the river flow causing erosion," Mapp said.
"At this stage we're building our technical understanding of the risks in the area and what might be possible to provide this community with some more time to manage their retreat."
He said the opening of the bar will be weighed against the risks.
"This is a highly volatile area and that makes this a very difficult engineering task."
Conversations between Mayor Scott and residents have been ongoing, and Mapp said it's been helpful having "good local knowledge" alongside technical information.
"We have been open with the community that this work comes with its own risks, and is most likely not going to provide a permanent solution, but will buy us time," he said.
"Both council and Environment Southland have been monitoring the area actively since the 2023 September floods," he said.
"This enables us to move quickly to open up the mouth of the Waiau and protect the properties and landfill from further erosion."
Environment Southland is planning the opening of the bar at the Waiau River with expert contractors.
Mapp said weather and tide consideration and working with Meridian Energy on river flows are key to opening the bar.
