Nearly 150 years after it was built for a paper mill, work has begun to demolish a 3m weir in Cumbria as part of a national effort to improve biodiversity by allowing fish and invertebrates to move more freely in the UK’s rivers .
Bent Boston is across the River Kent, an Internationally Important Site of Special Scientific Interest, home to white-clawed crabs and freshwater pearl mussels, as well as water duck’s foot, an oxidizing aquatic plant. But the river is in poor condition due to human interference over the centuries.
Pete Evoy, director of the South Cumbria Rivers Trust, said: “Removing the Boston weir will help re-naturalize this stretch of the River Kent, improve navigation for migratory species, reduce flood risks for residents and provide a 44% net benefit from biodiversity.
“We expect to see more fish, eels, invertebrates and other species,” he said. “This will be the first dam removal on the River Kent, but we hope it won’t be the last.”
One of 14 barriers on the River Kent, the 25m weir was built in 1874 to control the flow of water feeding Bowston Mill, which produced rags and ropes for the paper industry. The mill closed in the 1960s and was demolished, but the bulkhead was left in place.
It is estimated that there are around 50 to 60,000 dams, weirs and sluices on rivers in the UK, less than half of which have been mapped, including barriers built for industry, agriculture and flood defence. Many of them are now obsolete, but they continue to block rivers, damaging ecosystems.
Bowston is the biggest river barrier removal planned for the UK this year. Funded by the European Agricultural Fund for Rural Development, it is expected to take up to three months.
It took years to get the go-ahead to remove the Boston Dam. Photo: Courtesy of Ebsford Environmental
“The River Cumbria Restoration Strategy aims to remove as many disused weirs as possible and restore natural connectivity to our rivers,” said Oliver Southgate, River Cumbria Restoration Program Manager at the Environment Agency.
“The Boston spillway is one of the largest in the Kent catchment. Although the weir already has fish passages, the complete removal of the barrier will allow all fish species better access to upstream spawning habitats and help restore natural processes in this part of the river, benefiting people and The wild nature.
Getting to the point of removing the Bowston spillway was a long and challenging process, Evoy said, which began with getting consent from the owners of the James Cropper spillway, which continues to produce paper today.
“We have received approval to move forward to phase out in 2020 after years of discussion. Local residents have been very vocal in their disapproval, due to concerns about the perceived risk of flooding, riparian property and concerns that the removal will affect local biodiversity.
“The application had to go to a planning committee,” he said, “and was finally approved in February 2022 – five years after the initial feasibility report.”
Last year was a record year for dam removal in Europe, with at least 239 dams, dams and other barriers dismantled in 17 countries, including a dam that blocked Norway’s Tromsø River 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 by the slow pace of action in the UK and the lack of implementation of the promised legislation. “We are disappointed with the current situation,” Evoy said. “Most of these structures were built many years ago; they didn’t consider the environmental impact they would have.
“In an era of climate and environmental crisis, dam removal must be part of a nationally supported plan to repair the damage they have caused to our rivers.”
Spain removed 108 barriers from rivers in 2021, largely due to legislation that obliges the owner to pay for their removal after they stop using it. This type of legislation is seen as vital to the hopes of restoring the UK’s rivers. The Environment Agency has pointed to recent improvements to fish passages across England’s rivers, including the Severn and Tyne. But he was unable to provide a timetable for new legislation to remove the river barriers.
“Successive governments have promised legislation to free and restore the UK’s rivers for more than two decades, but have so far failed to deliver,” said Barry Bendall, chief operating officer of the Rivers Trust. “With the significant decline in our aquatic biodiversity, we urgently need to restore free-flowing rivers.
“But without legislation there is very little need for the owners of these barriers to do anything about it, so the UK’s outdated barriers will remain in place for generations to come.”
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