Planned bypass around beauty spot aims to boost biodiversity
It won’t be drivers but fish that will benefit from the proposal at the Horseshoe Falls, as Owen Hughes reports
MAJOR road-building projects may have controversially been put on ice by the Welsh Government, but that hasn’t put a stop to all bypasses.
In this case it isn’t drivers who would benefit from a proposed new route – but fish.
The proposal on the table concerns the stunning Horseshoe Falls, on the River Dee, near Llangollen.
The masterpiece of Thomas Telford engineering is where the Pontcysllte Aqueduct and Canal World Heritage site begins. He designed this weir to draw water from the River Dee into the canal, and it became a stunning addition to the landscape. But it isn’t good for all species.
The weir has been identified as one of the obstacles for the passage of fish along the Dee – harming the biodiversity of the river.
This has seen a new proposal put forward to help tackle the issue without harming the historic beauty spot.
Under the plan a new channel would be dug to link the river either side of the weir – allowing fish to bypass it completely.
A statement by Chambers Conservation said: “The proposal at the Horseshoe Falls is part of the wider
LIFE Dee River project, which aims to restore natural processes, features and habitats over a 55km or more stretch of the Special Area of Conservation (SAC).
“This project’s aims include improving longitudinal connectivity for fish and restoring or improving natural physical processes, features and habitats.
“Specifically, the Horseshoe Falls was identified as one of six obstructions to the passage of fish. The construction of a bypass channel will enable species such as salmon to travel the river and therefore greatly increase its biodiversity.
“This proposal will have an impact on the Grade II-listed Horseshoe Falls as well as the setting of other listed structures. The site is within the Pontcysyllte Aqueduct and Canal World Heritage Site and the HLW (C) 6 – Vale of Llangollen and Eglwys, eg Registered Historic Landscape.”
The scheme will create a channel under and across a loop of land to link sections of the river above and below the Horseshoe Falls. The central section of the channel (about half of its length) will be underground, with the field simply remaining largely as existing above.
At the inlet there will be a short section of open channel, basically only affecting the bank (the channel is culverted after around 10m). At the entrance to the culvert will be a precast concrete headwall; on top of this there will be a timber post-and-rail fence.
The open part of the outlet will extend much further into the grassed area and again will be surrounded by a timber post-and-rail fence. Both the inlet and outlet will have a ‘rock mattress’ on the ground, which will consist of large rocks carefully chosen to blend with existing geology. The sides of the open parts of the link will be grass over erosion-control matting.
A timber post-and-rail fence will be erected around the affected areas to stop cattle entering. Trees will need to be removed at the bottom (outlet) end.
Chambers Conservation explained how they would minimise the impact on the surrounding area.
They said: “The applicant has developed the proposals over the past few years to avoid and minimise harmful impacts. After initial discussions, as much of the drainage channel has been culverted as possible to reduce its visual impact.
“The type of fencing has been changed so that it sits comfortably within its agricultural setting and so that its materials (timber) will quickly weather down and be only minimally seen within views.
“There has already been some discussion on the types of rock forming the bed of the outlet and inlet channels – this can be carefully sourced to blend visually and geologically with the existing river stones, which will considerably minimise the impact.
“Whilst the culverted sections will have a concrete face, this will soften visually over time. One of the most important parts of any mitigation will be the sensitive replanting of affected areas – from ensuring the grass grows well on the channel slopes to the replanting of trees lost around the channel outlet.
“These trees are not thought to be particularly noteworthy specimens (they appear self-seeded) and therefore there may be some opportunity for enhancement, through selection of species that aesthetically and ecologically best benefit the immediate area.
“Whilst there are impacts on historic assets, the extent as to which this will be considered detrimental is subjective and even when it is considered in isolation it is marginal. However, these potential and marginal detrimental impacts can be weighed up against other gains.
“In this case, the gain to the ecological diversity of the river and the associated visitor benefits that it brings is considerable.”
They added: “To conclude, on balance, the proposed scheme does sustain and enhance the significance of the buildings, structures and areas in question as heritage assets. The scheme should therefore be supported.”
It will now be considered by planners at Denbighshire council.