Waitaki catchment didymo update

2 June 2006

Biosecurity New Zealand has issued the North Otago Irrigation Company an exemption under the Biosecurity Act allowing it to use potentially affected water in its scheme, Biosecurity New Zealand Director Post-Clearance Peter Thomson said today.

Biosecurity New Zealand has imposed a number of conditions on the company to ensure that all reasonable and practical measures are being taken to mitigate any associated risks.

“Our risk analysis of the scheme gives us confidence that the risk of spreading didymo via the scheme is minimal.”

On assessing the application Biosecurity New Zealand considered:

• The potential biosecurity risk of the activity spreading didymo
• The biosecurity benefits of the activity
• Whether the potential public benefits of the activity are such that, despite the biosecurity risk, the activity should be approved
• Possible mitigation measures including the cost and reasonableness of the mitigation against the biosecurity risk.

“While we have effectively allowed the irrigators to continue to operate, we have imposed strict conditions that will assist with the mitigation and management of the risk. We have been heartened by the response of the Irrigation Company to this issue and it fully supports the requirements we have imposed on it,” Mr Thomson said.

These include:

• Requiring the company to apply to the Otago Regional Council for a resource consent amendment to reduce the flow of 100 litres per second at Teschmakers with the aim of lessening the small chance of didymo establishing in the Kakanui stream.
• Establish signage along the Kakanui to raise awareness of the “check clean dry” message.
• To implement, at the company’s cost, a monthly sampling programme in the header pond. If didymo is discovered, Biosecurity New Zealand is to be notified immediately. If any further mitigation activities become available, the implementation of these will be discussed.
• To implement at the company’s cost the monitoring of salinity levels of the Waiareka / Kakanui estuary on a monthly basis until further notice.
• The company will employ decontamination measures for staff to prevent the transfer of didymo.

“While the risk of this scheme spreading didymo is small Biosecurity New Zealand is clear that fishermen and other river users still pose the biggest risk of spreading didymo. To minimise the risk of the spread we need all river users to check clean and dry every time they use a waterway,” Mr Thomson said.

Media contact:

Tina Nixon
Senior Communications Adviser
Biosecurity New Zealand

027 2232789