A group of citizen scientists claims to have discovered a previously unrecorded rare chalk stream on the Norwich Western Link road's route.

The Wensum Valley Citizen Science Group has met weekly over the past two years to carry out botanical surveys in the area where the controversial £274m road would be built.

And they say their evidence shows the River Tud deserves to be given special protection, with designation as an important chalk stream aquatic habitat.

They say their findings - lodged with Norfolk County Council as an objection to plans for the 3.9-mile road - show County Hall's own surveys of the Tud and Wensum river valleys were inadequate.

Liz Brandon-JonesLiz Brandon-Jones (Image: Liz Brandon-Jones)

Ecologist Liz Brandon-Jones, a member of the group, said: "Our fieldwork recorded particularly significant habitats of international, national and regional importance within a two kilometre radius of the proposed link road.

"We have found a seemingly overlooked rare chalk stream, which has never been properly recorded.

"It's an exciting discovery and right on our doorstep, but also a distressing one considering the proximity of the proposed road.

The citizen scientists claim they found an unrecorded chalk stream while surveying the River TudThe citizen scientists claim they found an unrecorded chalk stream while surveying the River Tud (Image: Liz Brandon-Jones)

"As a chalk river, the Wensum is classed as a rare Habitat of Principal Importance, of national and international significance – and the Tud is in the same category."

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Joanna GuthrieJoanna Guthrie (Image: Joanna Guthrie)

Norwich-based writer Joanna Guthrie, another citizen scientist surveyor, said good quality water that was untainted by pollution was crucial to support fen habitats and woodland such as alder and willow carr.

She said: "Our report makes clear just what a devastating impact the new road would have."

A visualisation of the Norwich Western LinkA visualisation of the Norwich Western Link (Image: Newsquest)

A spokeswoman for the county council, which has lodged road plans with its own planning committee, said: "The proposals have been developed in accordance with statutory processes and industry guidance and best practice.

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"The planning application documents demonstrate the extensive surveys carried out by the project team to understand the existing habitat and species found in the vicinity of the proposed route of the Norwich Western Link, and how we are taking account of this.

"As we said previously, we need some time to consider all the feedback provided through the consultation, and we will continue to work with the planning authority to respond to issues raised by consultees."

The council says the road, to connect the Northern Distributor Road to the A47, is needed to cut congestion, stop rat-running and boost the county's economy.