Swale Clearing

Dry Hills Estate Vineyard, Blenheim

Swales are one of those things that are easy to forget about — until they stop working.

DirtPro carries out regular swale maintenance at a Dry Hills Estate vineyard, clearing a 500-metre swale every one to two years to keep water moving freely across the site. Using the Hitachi ZX55 mini excavator, the full length can be cleared in a single day.

The blockage on this site builds up over time from a combination of vegetation growth and algae, gradually reducing the swale's capacity to carry water. Left unchecked, debris accumulates at the culvert at the end of the swale — and once that blocks, water has nowhere to go. It backs up, spills over, and starts eroding the surrounding land.

A day's work every couple of years is a small investment compared to the cost of repairing erosion damage or a washed-out culvert.

How do you know when your swale needs clearing?

• Water pooling or moving slowly after rain
• Visible vegetation or algae growth along the swale floor
• Debris building up at culvert or outlet points
• Erosion appearing at the swale edges

If you've got swales on your Marlborough property that haven't been touched in a few years, it's worth getting them looked at before the next big rain event.