HMWT Four people, standing by a river, with a bank and foliage on it, with a tree in the middle of the river. There is grass around the water and trees. HMWT

Work on the River Ash started in 2024 and was completed in August

A “ambitious” project to restore a 4.3-mile (7km) stretch of a rare chalk river to its original course has been completed.

Herts and Middlesex Wildlife Trust said the “landmark” scheme, on the River Ash, at the Easneye Estate, near Hertford, was “one of the largest of its kind in the county”.

The whole project took nearly eight years to plan and undertake, and also created a range of new wetland habitats.

Sarah Perry, river catchment coordinator for the trust, said it would help protect the area from flooding and “help to maintain the ecosystem balance”.

Sarah Perry A pond that has been dug, showing water in the middle, grass around it, a mound, trees in the distance and machinery to the right. Sarah Perry

Several ponds were created under the project

The trust said the River Ash is one of only around 260 chalk rivers in the world.

They are “rare and unique river systems” that support vulnerable and endangered species, including water voles, wild brown trout, and kingfishers.

“Despite how precious they are, chalk rivers have historically faced significant challenges from human activities, and they face the well-documented problems of pollution, over-abstraction and the growing impacts of climate change, with drought and flooding episodes becoming more frequent,” it added.

Paul Thrush A kingfisher bird, sitting on a branch, with a blue head, brown chest, and a long beak. Paul Thrush

The restoration will help birds like the Kingfisher, Herts & Middlesex Wildlife Trust said

The work included the creation of wiggles, where artificially straightened rivers are restored to their natural winding path and the reconnection of the river to its floodplain.

The river bed was raised with more than 3,000 tonnes of gravel, and more than 300 woody debris features were put in the water to create shelter for fish. Fifteen ponds were also created.

Sarah Perry A digger, in a wildlife area, with a river being worked on behind, with three other vehicles, around the site and two people standing by a car. There is grass all around the area. Sarah Perry

Diggers were brought in to restore the River Ash

Ms Perry said: “It’s rewarding to see such an ambitious project completed in Hertfordshire – the level of scale and impact is really exciting.

“This project not only provides hope for nature, but healthier rivers are good for us too; they carry fresh water, protect us from floods, help to maintain the ecosystem balance that we rely on, plus they support our wellbeing.”

She said working with the Easneye Estate showed “what other rivers in the county could be, which provides an exciting dynamic, and I’m hopeful this will lead to more positive change for rivers and nature’s recovery”.

HMWT Seven people, looking at the camera, and standing on a bank, by a river. There are two women and five men. They are all wearing trousers. HMWT

Volunteers helped to plant foliage around the site