Solomon Islands risks an environmental disaster unless immediate action is taken to prevent leaks at the country's only gold mine, the United Nations warns.

The Gold Ridge mine, operated by Australian company St Barbara, was found to have an extremely high level of contaminated water in its tailing dam following last month's flash floods.

The UN has recommended local authorities start the process of 'dewatering' to prevent any breach that may affect around 8,000 people living downstream.

It says preparations will need to start immediately for the process to be completed before the wet season begins in November.

"To be on the safe side and to avoid a potential disaster down the line, the water levels should be dropped," Sune Gudnitz, head of the UN Office for the Coordination of Humanitarian Affairs, told Pacific Beat.

Sorry, this audio has expired Sune Gudnitz, from the UN, explains the situation at Gold Ridge ( Brian Abbott )

"It will take time to lower the water level in a responsible way to dilute the water that comes out of the dam to have a minimal environmental impact."

Mr Gudnitz said water in the dam was polluted and believed to contain both cyanide and arsenic.

The UN Disaster Assessment and Coordination (UNDAC) team was deployed on April 23 in response to a request by the Solomon Islands Government.

'Living in fear'

The Prime Minister of Solomon Islands, Gordon Darcy Lilo, accused St Barbara of abandoning the mine when it evacuated all staff on April 7.

Mr Lilo's government has since barred several expatriate St Barbara workers from returning until an independent review of the situation is complete.

Local landowners have been critical of the government's response.

"It's not the right course of action. We need St Barbara right back in Solomon Islands on the ground to do the dewatering," said Dick Douglas, chairman of the Gold Ridge Landowners Council.

"They have the technical knowhow and they know the system."

Sam Maneka, chairman of the Metapona Downstream Association, agrees.

"The Prime Minister is wrong in his decision to disallow St Barbara to come over to Solomon Islands and stabilise the situation."

Mr Maneka says his people are "living in fear".

"I wonder when there's rainfall up there, if the people should be evacuated," he said.