Funding to tackle invasive willows

The Waihao Wainono Catchment Community Group is working hard to remove crack willow. PHOTO: SUPPLIED
The Waihao Wainono Catchment Community Group is working hard to remove crack willow. PHOTO: SUPPLIED
A new community-driven initiative has received the backing of the local water zone committee to tackle the growing threat of invasive willows along the Waihao River.

The Waihao Wainono Catchment Community Group has successfully applied for Lower Waitaki-South Coastal Canterbury zone committee funding to spray 400ha of crack willow.

Willows spread their roots into the riverbed, where their high water needs result in reduced flow and their rapidly decomposing leaves negatively affect water quality.

Waihao Wainono Catchment Community Group chairman Roger Small said the willow had become increasingly more problematic.

"There’s been a significant invasion of crack willow through the Waihao catchment over many years and it’s now getting to the stage where they’re completely blocking the river in some places."

Having run a family farm in Willowbridge, 7km southeast of Waimate, for more than three decades, Mr Small has seen the havoc caused by crack willow in the district.

He recalled a flood in 1986 where a large numbers of willows were uprooted, causing a blockage and collapsing McCulloch's Bridge.

"If we don’t do something, we can expect another disaster like that to happen again in a big weather event.

"It’s about building community resilience to these events and a big part of that is making sure we have clear fairways for the water to flow down."

The Waihao Wainono Catchment Community Group began the project in March and estimated it would require a 10-year commitment.

Thirty-six kilometres of willows have already been sprayed in the upper reach of the river.

Follow-up spraying will be undertaken to target regrowth.

A phased approach to the willow removal is said to help keep the community safe.

Mr Small said it was important the willows were correctly disposed of.

"Four hundred hectares of willows is a lot of timber that can do some serious damage in a flood.

"It’s critical we don’t overload the system with dead trees. We’re looking to remove what we can, particularly in sections of the river where there’s vulnerable infrastructure."

He said the catchment group was investigating wood-chipping options to counterbalance the cost of removal, which far outweighed the spraying itself.

The catchment group, which began in 1999 as the Waihao-Wainono Water Users Group, has the support and backing of a lot of landowners in the catchment, who have come on board to bring the willow-removal project to fruition, contributing both time and funding.

Mr Small said funding for initiatives like this was extremely important.

"As a group that is staffed entirely through volunteers, any funding we get goes directly towards getting things done on the ground.

"With a project like this, however, it’s all about the maintenance so continued funding will enable us to make a really big difference."