Projects/River Wardens Updates – Ouzel

February 2019

The Ouzel Enhancement Project: Making more of Leighton-Linslade’s hidden gem

The Ouzel Enhancement Project evolved from an Environment Agency Walkover Survey carried out in 2013, which identified the need to improve the habitats and channel diversity – the stretch alongside the Riverside Walk greenspace in Leighton-Linslade (owned by Central Bedfordshire Council) is a former mill leat and is straight, steep sided and over-widened.  This meant that for much of the year the river was sluggish and silty.  Naturally regenerating sycamores along the banks had grown to such an extent that in places very little light was getting into the channel, and there was little plant growth.  Coupled with Himalayan Balsam taking over large stretches of bankside and shading out native plant species, and signal crayfish (another invasive non-native species) burrowing into the banks and undermining them, causing erosion and sedimentation, the river didn’t have a lot going for it!

Over the last four years volunteers from the Greensand Trust, working with the Environment Agency, have carried out various tasks to help improve the river for wildlife and make it more attractive for residents and visitors.

Firstly the volunteers installed over 100m of hazel bundles along the edge of eroded banks, helping stabilise them, reduce the amount of silt getting into the channel and discouraging the signal crayfish.

Next the large willow trees growing in the channel, and ‘rafts’ of debris that had collected around them, were removed.   The bankside sycamores were thinned to let more light through the canopy, and they were used to create a series of “flow deflectors”.   These deflectors force what is currently a sluggish river around them, speeding up the flow and cleaning gravels vital for spawning fish and invertebrates.

Quote from Paul Wilkanowski, EA Fisheries Officer: “By felling trees already growing in the river, and using a small amount of this material for restoration, the works reduce the risk of flooding, while letting in more light to make a gloomy stretch much more attractive”.

Volunteers have also been involved in monitoring the invertebrates that live in the stretch, so that the impact of the improvements can be more accurately demonstrated.  The volunteers have surveyed three times a year for the last two years, and have built up a good baseline of evidence, against which future improvements can be measured.

During one of their sessions the volunteers also identified and reported a pollution incident that would otherwise have gone unnoticed.

Initial surveys of the river bed where the deflectors have been installed have shown that changes have already occurred, with sand and silt being washed away by the faster currents and exposing the gravels needed by a range of invertebrates and fish.  The deflectors have also provided ideal ‘refuge’ areas for fish seeking protection from flood waters, and a larder for the kingfishers, herons and little egrets along the river.

The project has been funded by Central Bedfordshire Council’s Planning Obligations Fund and the Defra Catchment Partnership Action Fund, with continued support through the Upper and Bedford Ouse Catchment Partnership and the Environment Agency.

Future plans include further bankside protection and tree thinning, and hopefully more deflectors – the aim is to use the works carried out so far to act as a demonstration before widening the scope of the project further.

-Jon Balaam (Greensand Trust)