A licensed release could slow flooding in the towns downriver.
Beavers will be released into the headwaters of the River Ardle next spring for the first time in roughly four hundred years, after the regional environment agency granted a licence for a managed reintroduction on Tuesday. The project will see up to four family groups, around fifteen animals in total, released into an unfenced stretch of upland streams above the village of Thornby. Scientists hope the dams they build will hold back floodwater and protect towns further down the valley.
The licence follows three years of surveys, public meetings and negotiation with farmers and landowners in the upper catchment. It was sought by a partnership of the regional wildlife trust, the university in Calder and two large estates that own much of the land around the release sites. The beavers will come from established populations elsewhere and will be health-screened and quarantined before release.
Engineers with teeth
Beavers are often described as ecosystem engineers. By felling trees and building dams across small streams, they create a chain of ponds, pools and wet meadows that slow the flow of water through a landscape. Studies of reintroduced populations elsewhere have found that beaver-dammed streams can reduce peak flows during heavy rain by a third or more, holding water back in the hills and releasing it gradually over days rather than hours.
That matters for Ardle and the riverside districts of Calder, both of which have flooded three times in the past decade. In the worst of those floods, five winters ago, the river rose more than two metres in eighteen hours and about 340 homes and businesses in Ardle town were inundated. Engineers have since raised flood walls in the town centre, but the agency has said it cannot keep building higher defences indefinitely.
“Beavers are not a silver bullet,” said Dr Ilse Marwood, the hydrologist at the university who has led the modelling work for the project. “They will not stop a once-in-a-century storm. But our models suggest that over twenty years, a healthy population in the upper catchment could take the edge off the kind of floods Ardle has seen repeatedly, and buy precious hours for people downstream.”
Marwood’s team has installed water-level loggers on eleven streams in the release area and will compare flows before and after the beavers arrive. They will also monitor water quality, sediment and the return of other species. Beaver ponds tend to attract dragonflies, amphibians, wading birds and otters, and can provide refuges for fish during dry summers.
Farmers’ concerns
Not everyone in the valley is enthusiastic. At public meetings in Thornby and Hollins Mill, farmers raised fears that beavers would flood fields, block drainage ditches and fell valuable trees. Some questioned what would happen if the animals spread beyond the release area, as they almost certainly will.
To address those concerns, the licence includes a management plan. A dedicated beaver officer will be employed for at least five years to respond to problems, and landowners will be able to apply for help to install flow devices – pipes that run through a dam and keep water at an acceptable level – or to protect individual trees with wire mesh. In extreme cases, dams can be removed or animals relocated, with the agency’s approval. A compensation fund of £120,000 has been set aside for losses.
Arthur Pennock, who farms 200 hectares of grazing land near the release site and initially opposed the scheme, said the management plan had brought him round, cautiously. “I am not against beavers, I am against being left to deal with them on my own,” he said. “If someone answers the phone when there is a problem, I can live with it. If they do not, we will be back here in two years having a very different conversation.”
What happens next
The release is planned for April, when the animals are least likely to be disturbed and food is abundant. Each family will be released into an artificial lodge near the bank of a chosen stream and tracked with tail-mounted radio tags for the first year. Public access to the release sites will be restricted for several months, though the wildlife trust plans to run guided evening walks from the summer.
Residents in Ardle who were flooded five years ago said they would watch with interest. “If a few rodents in the hills can keep the water out of my front room, they can have all the trees they like,” said one shopkeeper on the high street, who still keeps sandbags stacked by his back door.
