Thousands of pounds worth of work has begun on changing the appearance and shape of the River Bulbourne.
The sc heme, which started on Monday and will last up to four weeks, will narrow sections of the river between Fishery Road and Two Waters Road in Boxmoor.
The one kilometre stretch has been largely modified by man over the last 250 years, having now been degraded and unable to support the diversity of wildlife usually found in chalk streams.
Unrestricted grazing of the banks has also contributed to erosion and left little in the way of vegetation, which is crucial for the river’s health.
Chalk streams are a globally rare habitat and support a massive range of plants and rare animals.
More than £60,000 is being spent on the restoration, which is being funded by the Environment Agency, with financial contributions from the Box Moor Trust, as well as the Catchment Partnership Action Fund.
It will create a new course within the existing channel and regrade the banks in behind the new bank edges, reconnecting the river with its floodplain.
In addition, wetland scrapes will be created to provide more habitats for wildlife, while work will also be carried out to repair the fords to allow livestock and vehicle movements and prevent erosion in the future.
To protect the restored channel and allow the habitats to flourish, new fencing will be installed to control grazing on the site.
Some minor updates have already been carried out at the site, including a weir removal, installation of woody habitat features and improvements to some of the nearby trees.
Peter Ablett is chairman of the land and estate committee of the Box Moor Trust, which is helping fund the project and manages many acres of agricultural land in Hemel.
He said: “The work being carried out is essentially to narrow the river channel.
“Not a lot of people know that the chalk streams of the Chiltern are a unique worldwide geographical feature, and the work will try and restore a more natural chalk stream.”
And Nancy Baume, who is the project manager of the scheme for the Environment Agency, added: “After many years of planning and hard work from the partnership, we are really excited to see the restoration in action.”