Restoring Borck Creek to fish-friendly

Borck Creek between Berryfields and The Meadows is being turned into a meandering stream with deeper pools as part of an ecosystem restoration project to make it more fish-friendly.

Tasman District Council project manager Giles Griffith says the Waimea River was originally a braided river that meandered over the area and created the plains.

The creek was formed in one of the old, abandoned arms of the river.

During the development of the two subdivisions, the new creek became a reasonably straight channel through the middle of a wider floodway that was created to cater for big rain events in the catchment.

Now the council is recreating some of the original habitat that would have been present, by turning the straight lines of the low-flow channel into a meandering flow through the wider flood channel.

Deeper pools have been dug down to the groundwater and even logs and debris added into some corners to provide refuge for fish.

The stream will end up being longer with more wetland areas, which together will be beneficial for more species of aquatic life that he says will hopefully come over time.

“The more diversity in the channel, the more biodiversity you get. We’re trying to mimic nature.”

That has to be done without compromising the stream and the overall flood capacity and he says more length to the stream will be helpful for both objectives.

The project has been developed by stream and river consultant Sébastien Den Doncker who has been involved in similar projects in Europe and now lives in the region. He says the project is the future of how to manage rivers and streams in urban areas.

“You manage a flood problem and restore nature – and it’s a good opportunity for people to be in contact with nature. The social aspect has to be taken more and more into account around the world and it’s interesting it is happening here.”

He says the goal is to “give space to nature” and the end result will be a live ecosystem that evolves over time.

The stream already has longfin and shortfin eels as well as inanga (whitebait). Some plantings along the edge will provide not only shade but leaf drop into the water that feeds species such as freshwater koura (crayfish) – if they choose to live in the stream – and macro invertebrates.

Giles expects minor erosion along the stream banks and says that creates overhanging banks which provides protection for aquatic life. Being a flat channel, he says the stream does not have much energy and therefore cannot significantly erode.

To do the work, the project has a budget of $60,000 for the year, which will cover earthworks, planting and plant maintenance.