``We can't let lagarosiphon get established in Lake Wakatipu,'' Otago Regional Council chairman Stephen Woodhead said, in the face of questions at a draft annual plan hearing in Queenstown yesterday.
Water quality concerns were raised by Queenstown Grey Power member Kirsty Sharpe, who said if the weed became established in the lake, ``we are absolutely sunk''.
Cr Woodhead said the council agreed the weed could not become established. He noted lagarosiphon had been removed twice from Frankton Arm.
Last week, a Land Information New Zealand contractor sprayed the lakeweed in parts of the upper Kawarau River.
Cr Doug Brown said the ORC was working with several groups to combat lagarosiphon.
``From what we understand, they are working effectively.''