HONIARA – Health authorities in Solomon Islands have warned villagers living downstream of the defunct Gold Ridge mine on Guadalcanal island not to use river water because it could be contaminated by arsenic.

The warning follows the release of untreated water from the mine’s tailings dam into adjoining waterways.

Downstream communities using the Kwara, Tinahula and Matepono rivers are affected.

A community leader said last week they were “panicking” about the release of untreated dam water.

The mine’s owner, local landowner company Gold Ridge Community Investment (GCIL), announced at the start of the month it had begun a controlled removal of treated water from the dam, located about 40 kilometres from the capital Honiara.

There have been fears that the overfilled dam’s walls could collapse and send a torrent of water and toxic mining waste to communities downstream.

GCIL said controlled water releases began on March 29 and by last Friday, an estimated 150,000 cubic meters of treated and 92,000 cubic meters of untreated tailings dam water had been pumped out of the dam.

GCIL did not disclose that only days before the controlled releases began there had been an uncontrolled release of untreated water over the dam’s spillway caused by a period of heavy rain.

GCIL company secretary Ben Afuga told Radio Australia the situation was under control.

““I can confirm the test results have shown, in fact, zero concentration of cyanide and very low concentration of arsenic and other hazardous chemicals.”

But the Ministry of Health and Medical Services has released a statement advising downstream communities not to use rivers for drinking, cooking and bathing.

The ministry said the untreated water from the tailings dam “may carry sediment containing high levels of arsenic”.

Dr Gavin Mudd, head of environmental engineering at Monash University in Melbourne, backed the government’s warnings.

“We have an issue where we have water that we know is carrying arsenic and potentially other heavy metals into a local river system – which is far from an ideal outcome.”

Dr Mudd obtained the results of recent water tests taken downstream from the tailings dam after the earlier uncontrolled release of untreated water.

He said they indicated that there was “certainly an arsenic signature there” and the situation was potentially more serious than GCIL had described.

The results did not necessarily mean the water was unsafe, Dr Mudd added, but there was “not enough information to make a decision one way or the other”.

Dr Mudd said the whole situation was entirely avoidable.

“We know the basic engineering concepts in tailings dams and the way they interact with rainfall and storm events so I think at heart, we’ve consistently underestimated the long-term environmental risks,” he said.

“That raises questions about what’s next, how do we get this under control so that we don’t have waters carrying arsenic at low levels going down a river system?”

The mine was shut down in 2014 after damage from severe flash flooding left the tailings dam critically full.

After the Solomon Islands government’s refusal to allow the then owner, Australian miner St Barbara, to dewater the tailings dam, the Gold Ridge mine and all legal liability was sold to GCIL last year for $100.

- PNC sources