River Seven Skylighting 2018

The Seven Angling Club had initially sought advice from the Environment Agency and subsequently the Wild Trout Trust and the East Yorkshire Rivers Trust (EYRT). Their request was for advice to improve recruitment of native fish populations within the sections of the River Seven that they controlled.

Under the Water Framework Directive (WFD) this part of the river is failing good ecological status for self sustaining native fish species, during the delivery of this first phase it became apparent that the continuous tree cover on both banks created a dense shaded habitat that needed to be addressed.

More importantly, the work undertaken addressing the erosion measures would not deliver maximum effect unless more daylight could reach the river channel.

The riparian owner and fishing interests were involved in discussions to open up sections in the tree canopy allowing sunlight to reach the river bed.

Once agreement was reached, the EYRT appointed suitable contractors to undertake the work.

The aim was to concentrate on the main arable field which had a river connection of over 900m. A contract was drawn up to remove or ‘crown lift’ 1/3rd of this riparian field boundary. This was to be done in sections allowing for a mixed habitat of light and shade.

The Trust marked the sections where tree surgery was to be undertaken and following harvest of the field the contractors moved onto site.

Clear fell section: Note gravel bed exposed due to low summer flows now in full daylight.Many of the trees were multi-stem ‘pollard re-growth’ from previous clearance operations. The species involved were mostly Alder and Sycamore.

Looking upstream with the Sinnington WWTW outfall beyond the crossing log.Old logs were left in place as the bed scour and deep water created is beneficial to fish and invertebrates especially at low flows. These structures were checked and made secure.

Large timber being winched from the river.

Aerial view showing cleared section. Brash and logs separated for machine handling.

All brash was chipped, blown onto the river bank and levelled.

On completion of the felling the field was cleared of all brash and racked over.

Old timber removed from the river bed during the operation is stock piled on the bank ready for future LWD projects.

Timber stack ready for removal by road.

Monitoring

The Seven is one part of the EYRT’s sites for the Anglers Monitoring Initiative. The effects of the work undertaken will show over the next season or two. Similar work done on Pickering Beck showed a dramatic increase in the invertebrate population. It is believed that allowing more light to reach the riverbed that species of aquatic macrophytes will colonise, again increasing the numbers of invertebrates and areas of fry cover. A similar project to this was undertaken on the River Rye near Helmsley which saw a measured increase in the invertebrate population of 60% in twelve months.

 

East Yorkshire Rivers Trust - September 2018