Concerns around potentially hazardous material on the banks of the Mataura River in Southland are being taken to court.
The Environmental Defence Society is filing Declaration Proceedings against New Zealand Aluminium Smelters Limited (NZASL) concerning the storage of more than 10,000 tonnes of ouvea premix.
The premix can produce ammonia gas when it gets wet.
Environmental Defence Society chief executive Gary Taylor told Newshub the premix is being kept in a dangerous place, and something needs to be done.
"It's stored in an unsafe area we think, where it's at risk of inundation if the Mataura River floods."
In February, heavy rain across Southland caused the river to burst its banks and water drew close to the old paper mill where the premix is stored.
Although the paper mill remained safe from floodwaters, Taylor says the risk is still there.
"[The Mataura River] is prone to flooding, the concern there is that it got very,very close to creating ammonia gas."
As well as being harmful to humans, the gas is toxic to aquatic life.
In a worst case scenario, heat released by the reaction with water could generate a fire at the paper mill along with releasing ammonia gas.
The proceedings will determine whether the NZASL is responsible for the removal of the premix.
