Clutha River’s willows get the chop

A familiar stand of willows gracing the south bank of the Clutha River in Balclutha received a dramatic makeover last week.

The row of 48 trees split by the Balclutha Bridge was given a short, sharp, military-style haircut by Otago Regional Council contractors during Friday and Saturday, in a move to reduce "slash" entering the waterway, and possible risks to the Clutha floodbank.

Although picturesque, the trees sat within a known flood zone and could cause a breach in the flood bank were they to topple, ORC said.

The trees were inundated during a serious flood last month when flows in the river reached a 20-year high.

That event had precipitated the recent work, ORC manager of operations Nineva Vaitupu said.

"These trees were top heavy, which could compromise the integrity of the flood bank terraces if there is another flood event."

The Landcare Research website describes willow management as "complicated".

When used correctly, willows can offer riparian shelter and bank stabilisation, but can also block waterways and scour stream banks when poorly sited.

Mr Vaitupu said ORC regulations required any trees adjoining riverbanks to be properly managed and maintained to avoid negative impacts on waterways.

The willows in question would return to growth during the summer.

- John Cosgrove