The Great North Fen, the creation and restoration of fenland along the banks of the River Skerne to the east of Newton Aycliffe, was originally intended to cover 500 hectares when the plans were first mooted in 2018.

However, Jim Cokill, director of Durham Wildlife Trust, told a gathering of funders, partners, and other supporters at Hardwick Hall Hotel, near Sedgefield, that the project was being increased to 850 acres.

“It will probably cost £38m, which is an enormous amount of money, but it is has the potential to generate £130m of income,” said Mr Cokill. “This could come from a variety of sources including environmental grants and new approaches to land management and the sale of environmental credits”.

The announcement came at an event to mark the end of the Discover Brightwater Landscape Partnership, launched in 2018 as a £3.3m project to “restore, reveal and celebrate life around the River Skerne”.

One of the main legacies of Discover Brightwater is the creation of Bishop’s Fen, which covers 23 hectares of improved wetland habitats to the south of Bishop Middleham, where scrapes and channels have been created in the pastures.

Bishop’s Fen is the first part of the proposed Great North Fen, which will stretch down from Bishop Middleham to Preston-le-Skerne, near Newton Aycliffe.

After the gathering at Hardwick Hall Hotel, those attending the event were taken by bus to Bishop’s Fen, where the site was officially opened and blessed by the Venerable Rick Simpson, Archdeacon of Auckland, and the Church of England diocesan lead on the environment and climate change.

“I am honoured to be here today – this is something close to my heart. The opening of a new nature reserve and a project on this scale is so exciting,” said the Archdeacon, who cut a willow to open the fen.

“I wish Durham Wildlife Trust, and everyone involved with this fantastic, strategic project, every success.”

The Discover Brightwater Landscape Partnership took its name from the Old Norse word “skirr”, meaning “bright and shining”. It was supported by the National Lottery Heritage Fund and made possible by those who play the National Lottery.

The project brought together local businesses, landowners, local authorities, environmental agencies, community groups and wildlife organisations, with Durham Wildlife Trust as the lead partner.

Mr Cokill said the creation of the Great North Fen would be a boon for waterbirds, such as golden plover and lapwing. Even more important was the restoration of the wetland plants such as common meadow rue, water crowfoot, water plantain, water violet, water horsetail, celery-leaved crowfoot, sharp-flowered rush, great spearwort, and great pond sedge.

“If we create the habitats, species will return,” he said.

Paul Black, Discover Brightwater’s manager, said the success of the initiative had been due to “a fantastic partnership”.

“It hasn’t been easy, and there have been lots of challenges along the way, but so much has been achieved,” said Mr Black.

“It has been a huge project. We have worked with thousands of local people, raising awareness of nature and what we have on our doorstep. We’ve had 19 workstreams, 50 projects and, in six years, £5m has been spent making a real difference to this area, with the Great North Fen becoming its legacy.”