River Seven Habitat Improvements 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, therefore a project to improve native fish stocks would add value to all parties concerned.

The EYRT suggested using tried and tested techniques from the River Habitat Restoration tool box to address these failings.

Introducing Large Woody Debris (LWD) to deflect the flows away from damaged banks and protect these friable sections from further erosion. The Seven, as with other moorland rivers, carries vast quantities of sediment into the Derwent which needs to be addressed at water abstraction points downstream.

This ‘Green engineering’ entails using local materials that will provide a diverse flow regime, more in stream habitat, cover for both adults who maybe predated upon but also refuges for juvenile brown trout and grayling. In turn this habitat will provide a more diverse flow regime that in turn maintains clean, well aerated gravels necessary for invertebrates and successful fish spawning.

Following on from the initial walk over with the Wild Trout Trust, the East Yorkshire Rivers Trust submitted a funding application to the Environment Agency for a Fisheries Improvement Grant.

This application for grant funding was successful.

An application was made for a ‘Flood Risk Permit’ which was subsequently granted. The project site was to start as the river passed under the A170 and continue downstream approaching Sinnington Lodge Farm, a distance of about 1.8 km.

YWS Biodiversity Grant

Due to unforeseen delivery problems on a site at Norton Ings, funded through a YWS grant, it was agreed that the Trust could transfer this funding to a project where all permissions were in place and that could guarantee delivery. This additional funding has enabled the Trust to build on work already planned under the EA Grant.

Specifically, additional numbers of flow deflectors, tree ‘kickers’, have been installed and small areas have been felled allowing sunlight to reach the river bed.

The Trust intends to continue the removal of tree cover in short sections. This will provide the variation of shade and light that improves the river environment. Some of this work has been completed by EYRT staff to date. However due to ground conditions and riparian agricultural crops this will be completed in autumn outside the bird nesting season.

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.

Maintenance

The EYRT will advise the angling club on best practice and methods in maintaining the LWD and marginal sections.

Methods

Using the best practice methodology and the in house expertise the works to create in stream habitat commenced in early January 2018. Up to date 11 days using a three man team have created 32 individual points along the river from below the A170 to a point just short of Sinnington Lodge.

Materials used were sourced on site using LWD (Large Woody Debris) to provide diversity of flow, fish refuges, tackling erosion and increasing habitat for invertebrates.

Further works are planned in co operation with the Seven AC and the riparian owners to look to improve the self sustaining native fish populations.

Willow trees growing on the bank being used to protect erosion downstream. The trees were hinged leaving them alive which means they can continue to grow and provide long term protection.

Close up showing trees felled and hinged. Note additional cabling securing trees to original stumps.

Tree ‘kicker’ being drilled to take a 2000mm x 16mm rebar pin securing it in place.The tree brash is winched to the river bank and pinned in place.

Pin being driven into river bed using petrol post driver.

Tree felled and pinned to river bed and river bank, this will address erosion; habitat creation for both juvenile and adult fish and create more habitats for the food of fish.

Showing the stainless steel 8mm cable and fittings securing the felled log using the tree stump as an anchor.

Tree ‘kicker’ following a short period of high water. Debris caught in small branches and sediment around the base of the branches.

Long section of eroded bank. The central part now protected with LWD.

Pool and riffle section. Hinged tree in middle distance creating flow diversity and cover.

Forked Sycamore, cabled and pinned covering an eroded bank.

Manufacture of ‘cover logs’. Sycamore is felled, split and drilled. Above: view of pins ready to be fixed to river bed.

Submerged logs showing diverse flow patterns resulting in some sediment retention and cleaning of gravels.

The photograph above shows a view looking downstream before any introductions of the LWD deflectors, note the uniform flow pattern with little suitable habitat.

The Trust wishes to thank both the Environment Agency and Yorkshire Water Services for their support which has made the delivery of this project possible.

 

East Yorkshire Rivers Trust 2018