Horizons Regional Council’s weed harvester has been out on Punahau/Lake Horowhenua again for its annual lake floor mowing duty.

Two skippers, at times three, work 12-hour days, seven days a week, for six weeks each January and February to get the job done.

“The harvester is classed as a boat, so we all have skipper qualification,” says one skipper, Julian.

The Horizons weed harvester is a big one. Only Bay of Plenty Regional Council has one the same size, which services lakes around Rotorua. The local harvester is in its third year of operation.

“Prior to that we ran a trial, so we have been out here four years now,” Julian says.

Work depends on the weather, and it’s dependent on wind, rather than rain, because wind makes waves too high.

Last year the council harvested 400 tonnes of oxygen weed and curly pond weed. Mowing them is an ongoing task.

“These weed species regrow every year,” says Horizons freshwater and partnerships manager Logan Brown. “Curly pond weed has an annual cycle, producing a semi seed that helps it regrow, while oxygen weed just regrows every year.”

Logan says the weed harvester doesn’t pull weeds out of the lake bottom, but mows it down just like a lawnmower –  about 300mm from the bottom.

In the huge mountain of weed being brought on land each day it’s clear to see that the cut edges are sharp and whole bundles show the same even cut.

Every hour of so the harvester pulls into shore to off-load the weeds it has collected.

Whaea Deanna Hanita-Paki, a Horowhenua Lake Trust trustee, is on hand to load three wheelie bins of samples each time the harvester returns to shore. Those bins are thoroughly checked and any eels and fish are pulled out, recorded and then released back into the lake.

She has found fish species, eels and even shellfish among the cut weeds.

“We say a karakia every morning for the eels, to tell them to get out of the way of the harvester, and we have a protecting role regarding machinery, too.

“We are the guardians, who walk with the workers, so they can go into the lake safely.”

In the evening after the work is done there is another karakia.

Logan is chuffed to be involved with the weed harvester, as well as the Arawhata Wetland.

“I have been doing that since 2011. We work closely with both Muaūpoko Tribal Authority and the Horowhenua Lake Trust.

“We’re always looking for ways to make our work more efficient and as part of that we have changed from using contractors to employing staff on the project.”

The boat ramp for the weed harvester is near the Arawhata Stream and its sediment trap on Hokio Beach Road, from where water flows into the lake.