Mangatāwhai / Black Valley Wetland 2024

Ecological and cultural benefits for Tasman’s wetland areas have been realised with our Mangatāwhai / Black Valley Wetland project, just north of St Arnaud.

Earthworks took place over two weeks in March 2024, involving the plugging and filling of areas where land had previously been drained to create productive land.

This work continued the efforts started by the Department of Conservation around 15 years ago.

Wetlands are critical as being sponges or kidneys to not only clean the water but also hold onto it – that’s why this project is important.

Further enhancement was carried out through weed control, fish recovery, and sediment erosion control, with 3,284 plants planned over the next two years.

Where the drains were difficult to access by the digger, a helicopter provided a practical alternative for depositing the soil.

Our partnership with local iwi enabled some innovative approaches to the project – most notably through the use of harakeke geotextile baskets for plugging old drains.

These baskets reinforce the earth plug to ensure that it resists erosion – enabling plants to establish themselves and stabilise the plug.

“Using these baskets not only supports mātauranga but also reduces the number of helicopter trips required in future,” Blair says.

The Mangatāwhai / Black Valley project was made possible by the Ministry for the Environment’s Freshwater Improvement Fund (FIF) with in-kind contributions from the Council.

The wider FIF programme has enjoyed some pleasing successes in reaching the halfway point of this five-year programme.

So far, 21,000 hours have gone into protecting and enhancing wetlands, as well as 28,170 plants, 210ha of weed control and 82ha of pest animal control.