During these uncertain and unprecedented times, we are delighted to have finally completed our Heritage Fund supported by the National Lottery, River Witham habitat enhancement project in Dysart Park, Grantham. The project was postponed from last autumn by unusually high rainfall.
Covid-19 prevented us from safely engaging our trusty team of volunteers, so it was down to Lions Environmental Contractors to deliver the project. All of the necessary permits were secured, and ecological surveys carried out in advance, keeping wildlife disturbance down to a minimum.
On a sunny September morning Lions began creating natural berms in the river channel. With lots of trees growing on the river bank and shading the water course, we decided to employ a technique called tree hinging for this project. This used the natural materials that were already abundant in the area and at the same time opened up the canopy to let some light through to the watercourse.
Trees were partially felled and bent around to form the framework for the berms (low level shelves in the water). Leaving part of the trunk attached at the base to anchor the tree in place, wooden stakes and wire were then used to secure the structure, which had been backfilled with brash and faggots (bundles of hazel twigs).
The berms not only provide shelter for fish and other river dwellers, but also help to recreate the ‘wiggle’ that, would occur naturally in a river. This action allows pools of deeper, calmer water as well as shallow water riffles enabling more natural river processes. The faster flowing water scours the riverbed, cleaning silt from the gravel and making it better for spawning fish.
In higher flows silt is trapped in the berms as the water passes over them, which will, over time, enable plants to take hold until the berm becomes a natural part of the riverbank. After only a few days the wiggle was already apparent and just two weeks after work was completed the berms have already begun to trap silt.
Not only are we pleased with the results, it seems the local residents are also happy to have a little more light and a much better view of the river. This stretch will contribute to the wider South Kesteven District Council (SKDC) Witham/Slea Blue Green Corridor Project. Over time it will improve the area for wildlife, and invertebrate surveys carried before the project started will give us a benchmark for future comparisons.
A big THANK YOU must go out to SKDC for their support, Nick and Laura at Lions Environmental and the Environment Agency for their expert advice.
Images by David Martin