River Coln, Gloucestershire

The River Coln runs off Cotswold Limestone and is a popular fishery, with sections fished by several private syndicates and clubs including the Cotswold Flyfishers. Having carried out a couple of Advisory Visits on different beats, it was apparent to Andy Thomas, the WTT Conservation Officer and Vaughan Lewis, working on behalf of the newly formed Cotswold Rivers Trust, that the river was suffering from a significant decline in weed growth over long stretches and this was probably resulting in a deterioration in fly life and fish populations. The fishing interests have been aware of the decline for some time and many are particularly concerned about the lack of water crowfoot. Meetings with the clubs, landowners and the EA and a review of the considerable body of research on water crowfoot led to no definite conclusion as to why the crowfoot was in decline. Water quality, flows, swans – the usual suspects were considered. None pleaded guilty but all were probably implicated.

Addressing the root cause of a problem is always better than fixing the symptoms, but in this case it was felt that some remedial habitat works would be better than no action. Fishery owner John Paine was concerned that his stretch was not only suffering from lack of weed, but banks were collapsing due to signal crayfish burrows. So began a partnership project designed to create more in-channel cover in lieu of any weed but also to promote  an environment where the weed might be able to recolonise. In addition to this stretch, the project also looked to work with Robert Mitchell, representing the Dudgrove Syndicate and Ben Pollard from the Coln Lakes,

The plan was supported financially by the Environment Agency and by Thames Water – but even better, both those organisations came to help with the work! Paul St Pierre of the EA, accompanied by a team of EA fisheries and biodiversity technical officers contributed, along with Rupert Newby and Claudia Innes of Thames Water.  The crew was joined WTT staff, volunteers and contractors in carrying out the project. Work included:

  • The introduction of cobbles to create more bed stability and a better environment for rooted submerged plants.
  • Thinning out dense cover along the banks to let in more light and provide brushwood material.

Large woody flow deflectors River Coln

 

  • Creating large woody debris flow deflectors to create variation in flow and substrate.

 

 

 

 

 

  • Re-profiling of signal crayfish damaged banks
    and protection with large and coarse woodyre profiling banks Kris Kent
    debris

 

 

 

 

 

 

 

  • Installation of faggot bundles
    (made from brushwood arisings) in the channelinstalling mid channel brushwood bundles
    to act as a surrogate for the missing water
    crowfoot by providing food for invertebrates,
    cover for fish and a trap for silt.

 

 

 

 

 

 

 

  • Installation of brushwood bundles to protect eroding banksprotecting banks with brushwood

 

It is hoped that this mixture of habitat work will help create the environment where the remaining crowfoot will flourish again, and we will be working with the EA to monitor progress. 
For now, at least the fish and invertebrates have an alternative source of food and cover, and owners and fishermen along the Coln will be alert to any problems and watching for developments, good and bad