Lake Benmore Gets Clean Bill Of Health

30 September 2005

Lake Benmore Gets Clean Bill Of Health

Lake Benmore has been given a clean bill of health after four reports all confirmed mercury levels in the lake are well within safety limits, the Treasury announced today.

The reports were undertaken after information emerged last year that drums containing porcelain mercury arc valves were disposed of in Lake Benmore by the New Zealand Electricity Department on two occasions, in 1969 and 1973-74.

Environmental management specialists URS New Zealand were commissioned to assess the potential risks from mercury in the valves.

“The URS report concluded that while there may be some residual mercury in the valves, the levels are likely to be very low and pose no environmental risk,” said the Treasury’s Manager of Commercial Investments, Chris White.

“As a further precaution, separate reports were commissioned from Transpower, the Institute of Environmental Science and Research, and Landcare Research. Every report has confirmed that the risks are negligible and no remedial action is needed.

“There has been no disposal of mercury arc valves in Lake Benmore since 1974 and we are not aware of this happening in any other lake or waterway in New Zealand.”

The Landcare Research report involved catching and testing trout from Lake Benmore to measure mercury concentrations. The mercury levels were 0.162 milligrams per kilogramme (mg/kg) in female fish and 0.153 mg/kg in male fish. These concentrations are well below the conservative safety limit of 0.5 mg/kg prescribed in the Food Standards Australia New Zealand Code.

Environment Canterbury, as the agency responsible for monitoring soil and water quality in the region, has been involved in the Landcare Research study.

Ministry for the Environment Standards Senior Advisor Jonathan Coakley commended the responsible approach taken to risk assessment since the disposal of valves in Lake Benmore came to light.

“The potential risks have been investigated promptly, cautiously and thoroughly. Based on the current findings in the reports, we have confidence that mercury levels in Lake Benmore fish are safe and pose no health risk,” said Mr Coakley.

There will be ongoing periodic tests of mercury concentrations in Lake Benmore trout to ensure mercury levels remain within strict safety limits. These tests will include comparing mercury levels in fish from other lakes in the area.

ENDS