Almost 150 years after it was built for a paper mill, work has begun to demolish a 3 meter high weir in Cumbria as part of national efforts to improve biodiversity by allowing fish and invertebrates to move more freely along the along UK rivers.
Bowston Weir is across the River Kent, a Site of International Importance of Special Scientific Interest, home to white-clawed crayfish and freshwater pearl mussels, as well as crayfish goose, an oxygenating aquatic plant. But the river is in poor condition due to human intervention over the centuries.
Pete Evoy, director of the South Cumbria Rivers Trust, said: “The removal of the Bowston Weir will help renaturalise this section of the River Kent, improve navigation for migratory species, reduce flood risk for residents and provide a gain net biodiversity of 44%.
“We expect to see more fish, eels, invertebrates and other species,” he said. “This will be the first weir removal on the River Kent, but we hope it will not be the last.”
One of 14 barriers on the Kent, the 25m wide weir was built in 1874 to control the flow of water that fed Bowston Mill, which made rags and ropes for the paper industry. The mill closed in the 1960s and was demolished, but the weir was left in place.
It is estimated that there are around 50-60,000 dams, weirs and culverts on UK rivers, less than half of which are mapped, including barriers built for industry, agriculture and flood defences. Many are now obsolete but continue to block rivers, harming ecosystems.
Bowston is the biggest river barrier removal planned for the UK this year. Financed by the European Agricultural Fund for Rural Development, it is expected to last up to three months.
“The Cumbria River Restoration Strategy aims to remove as many disused weirs as possible and restore the natural connectivity of our rivers,” said Oliver Southgate, Cumbria River Restoration Program Manager for the Agency. environment.
“The Bowston weir is one of the largest in the Kent catchment. Although the spillway already has fishways, complete removal of the barrier will allow all species of fish to have better access to spawning habitat upstream and will help restore natural processes on this part of the spillway. river, for the benefit of people and wildlife.
Getting to the Bowston spillway withdrawal point was a long and arduous process, said Evoy, who started by getting approval from spillway owners James Cropper, who continues to make paper today.
“We have obtained approval to move to phase-out in 2020, after years of discussions. Local residents expressed disapproval, due to concerns about perceived flood risk, waterfront property, and fears that the removal would affect local biodiversity.
“The application had to go through a planning committee,” he said, “and was finally approved in February 2022 – five years after the initial feasibility report.”
Last year was a record for dam removals in Europe, with at least 239 dams, weirs and other barriers removed in 17 countries, including a dam that blocked the Tromsa River in Norway for more than 100 years. The recently launched Open Rivers program will invest €42.5m (£36.5m) over the next six years in removing river barriers across Europe.
But conservationists and river experts are concerned about the slow pace of action in the UK and the failure to deliver promised legislation. “We are frustrated with the current situation,” Evoy said. “Most of these structures were built many years ago; they did not consider the environmental impacts they would have.
“In an era of climate and ecological crisis, the removal of weirs should be part of a nationally supported plan to undo the damage they have caused to our rivers.”
Spain removed 108 river barriers in 2021, largely thanks to legislation that requires the owner to pay for their removal once they stop using it. This type of legislation is seen as vital to the hopes of restoring Britain’s rivers. The Environment Agency has highlighted recent improvements to fish passages across English rivers, including the Severn and Tyne. But he was unable to provide a timetable for new legislation to remove river barriers.
“Successive governments have promised legislation to free and restore rivers across the UK for more than two decades but have so far failed to deliver,” said Barry Bendall, chief operating officer of the Rivers Trust. “With the dramatic decline in our aquatic biodiversity, we urgently need to restore free-flowing rivers.
“But without legislation, there is very little imperative for the owners of these barriers to do anything about them, so outdated weirs across the UK will remain in place for generations to come.”