Lake weed at the top of the Ahuriri arm on Lake Benmore is to be sprayed by helicopter and boat later this month using two different chemical.
The work, to control the problem lake weed lagarosiphon, is being carried out by Land Information New Zealand and Meridian Energy Ltd.
A warning has been issued not to take drinking or irrigation water from the area that has been sprayed for 24 hours after the control work.
Lagarosiphon has established itself on the delta at the Ahuriri rivermouth on the lake. Similar control work has been carried out in the past.
This time, a helicopter will be used to spray a new chemical, Aquathol K, which has the potential to kill the weed rather than just control it. A boat will spray the chemical diquat.
The control work is scheduled to be carried out between April 20 and May 15, subject to conditions.
A harmless tracer dye will be released before or during the spray operations to determine dilution and dispersion characteristics in the target weed.
