The high cost of containing the spread of an exotic water weed in Lake Taupo should be shared with other agencies, according to Environment Waikato.

The Council is dealing with the spread of the oxygen weed Egeria densa in the marinas of Lake Taupo – and the cost of containing it by dredging is likely to exceed $180,000. That’s more than it is prepared to spend on one weed problem, and it will ask Taupo District Council and Ngati Tuwharetoa to share the costs.

This week’s Council meeting heard that eradication is impossible and the weed may be contained by dredging in the Taupo outlet marina to ensure it doesn’t spread, an operation that will have to be repeated annually. Biosecurity Group Manager John Simmons said substantial gains could be made in the Kinloch marina as long as public awareness was raised, marina management assisted to prevent spread by boats and harvesting practices refined. The exotic plant was quite aggressive and could potentially dominate the biodiversity in the area.

Chairman Neil Clarke said it would be very difficult to ensure that it wasn’t dragged to other parts of the lake if some boat owners didn’t know they had it on their boats.

Cr Jim Howland said the Council was sitting on a time bomb, with worse plants sitting in aquariums around the country which could get into waterways. Cr David Peart said he was appalled that the weed could not be dealt with.

“Why aren’t we hitting it as hard as we can? Controlling it will cost us more in the future and we should be trying as hard as possible to get rid of it. Who is responsible for bringing in these weeds illegally?”

Cr Helen Lane said the cost of the operation was “out of our league” and needed a contribution from other agencies.

“If we don’t do this where is it going to end?”

Cr Andra Neeley said the cost was far too much to spend, given that the Council did not have unlimited money.

Cr Evan Penny said it was “unbelievable” that ports and airports were open to invasive pests, and regional councils needed to get together and tell Government that they were being let down on border control.

“We have one new plant pest after another and urgency is needed to control them.”

A scientist from the National Institute of Water and Atmospheric Research is to be asked to provide urgent advice to a special meeting on what can be done to control Egeria densa.