Afon Iwrch Rehabilitation Project

Afon Iwrch Rehabilitation Project

Background and scope

 

The Afon Iwrch Rehabilitation Project was an Environment Agency Wales (EAW) Challenge Fund project which took place in 2009.  EAW, now Natural Resources Wales (NRW) established the fund to assist the new Rivers Trusts in Wales gain expertise in designing and managing habitat projects. They also provided expertise and guidance during the project and the Trust was able to utilise authorised and approved contractors. The Clwyd & Conwy Rivers Trust, now the Clwyd Conwy & Gwynedd Rivers Trust, was successful in being awarded two Challenge Fund projects, the other one being on the Afon Elwy at Pont y Ddôl. The scope of the Afon Irwch project was to improve the habitat for spawning salmonids and for other vulnerable wildlife such as voles and bats by creating a buffer zone on each bank of the stream. Serious bank erosion required remedial action and an impassable man made weir was to be removed.

The Afon Iwrch is an important salmon spawning stream flowing into the Afon Conwy upstream of the Conwy Falls. It also has a good stock of wild brown trout and loach but has suffered in the past from random sheep dip pollution incidents. A habitat scheme had been carried out by Environment Agency Wales over ten years ago but this required serious remedial and other work due to incidents of bank erosion, partially caused by fallen trees.

The original scheme extended to just less than 1 km of the stream but a weir constructed as a smolt trap about 200 metres below the top of the scheme effectively barred all upstream migration beyond that point.  Above the scheme for about 1 km lies an SSSI where the banks of the stream have been protected from grazing by the construction of stock proof fencing. Removing the weir would open up another 2 km of good spawning habitat. Water quality monitoring by EAW staff had controlled the historical pollution incidents and the stream supported good populations of invertebrates and juvenile fish. The land surrounding the stream is owned by the National Trust and is leased to two tenant farmers, one participating in the Tir Gofal scheme.

1

The previously impassable concrete weir after it was breached

The work carried out

 

The work undertaken was in line with the site management plan that had been prepared and primarily involved renewing fencing on both banks of the stream to ensure a protected buffer strip to prevent grazing. A drinking gate that had silted up due to minor river bed change was replaced by a drinking trough utilising mains water supply from a nearby barn. Additional swing gates were installed towards the top of the scheme creating two drinking points enabling an additional 100 metres of bank to be fenced. This extended the scheme to meet up with the already fenced SSSI.

 

An impassable concrete weir was breached enabling migratory fish to obtain upstream access opening up an additional 2km of good spawning habitat denied to the fish since the weir was constructed.  Significant work was carried out to repair the banks of the stream where they had suffered erosion. The worst example required stonework and bank re-profiling whereas the other instances were repaired using willow spiling and the removal of fallen trees which were diverting the stream into the bank in high flows.  Some coppicing of willow around the stream was done to allow more light into certain stretches of the stream that were ideal habitat for salmon parr and a general tidying up of overgrown trees was conducted by volunteers.

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A section of the stream just after fencing had been completed to provide a buffer zone

                                                                                Lessons learned

The concept of using a real habitat scheme as a training exercise worked very well, minimising resources from EAW and maximising the practical experience to the Trust in how to plan and execute such schemes in the future. The importance of getting the landowner and tenant farmers involved early on in the project minimised any disruption to the smooth execution of the work programme.

Using pre-approved contractors and getting guidance from EAW staff on likely costing levels (for example cost of stock proof fencing per metre) was very helpful in managing the contractors to budget and to obtaining a high value result. National Trust staff were very helpful in planning and gaining assent to the habitat scheme and contributed valuable resources at no cost by removing fallen trees as part of the scheme.

The two tenant farmers were extremely cooperative, recognising that in exchange for giving up a little land for the buffer strips they would have significant lengths of fencing repaired or replaced at no cost to them. The farmers also agreed to monitor the fencing and make minor repairs to it whenever it was needed.  Equally, they promised to inform the Trust in the case of any severe damage to the habitat scheme fencing. The Trust now carries out ongoing invertebrate monitoring of the stream within the habitat boundaries and generally excellent levels of invertebrates are observed.

More photographs relating to the work carried out as part of the this scheme can be seen in the Gallery section of the website