9. Gadebridge Park river restoration project

Aims: Involve people with their local waterbodies; Improve wildlife corridors; Manage flow; Work together

Water body: River Gade

Project description

The Environment Agency, together with project partners Dacorum Borough Council and Affinity Water, has restored a 450-metre stretch of the River Gade - a globally rare and valuable chalk stream - in Gadebridge Park, Hemel Hempstead.

For hundreds of years, the River Gade in Gadebridge Park flowed down an artificial channel created to supply water to the now demolished Bury Mill. Its unnaturally wide and straightened course was isolated from its groundwater source, perched above the valley bottom and suffered from sluggish flows and gravel beds choked with silt and overgrown vegetation. It lacked any of the characteristics of a natural chalk stream. Before its restoration, the ecological health of this stretch was last determined as ‘poor’, and a fish survey in 2021, when the river was struggling to recover from prolonged dry weather, described the results as ‘near desolate’.

Completed in July 2025, the restored channel is now realigned back to its natural position through the centre of the park in the valley bottom. The new channel provides multiple benefits for people and wildlife:

- The river is reconnected to its floodplain and groundwater source. Spring flows, once lost to the River Gade, have been rerouted back into the channel. This will improve its resilience to extreme weather and climate change, including both low flows and flooding. This, in turn, will provide more long-term stability and protection for its wildlife.

- By moving the channel from its ‘perched’ position above the floodplain back to the valley bottom, flood water can now drain back into the channel. This will help to reduce the extent and duration of the pooling of flood water in the park, meaning that activities can get back to normal more quickly.

- A huge barrier to fish movement has been removed by replacing the old gauging station with modern technology that uses ultrasonic rays on the riverbed. This means the Environment Agency can continue to collect vital river flow data - supporting their flood warning system - but without impacting river habitats and wildlife.

- A winding varied channel has been created with gentle meanders and gravel features typical of natural chalk streams. This provides a range of habitats for wildlife to thrive – for instance, deep calm pools of water where animals can take refuge, as well as shallower, faster flowing water for fish to spawn. Once fully established, the wide planted banks of the river will also provide a corridor for wildlife, including perhaps in the future even burrows for water voles!

- A wildflower meadow, two new bridges and a river access point allow everyone to safely get closer to nature and enjoy this unique environment.

And the results are already looking promising…

In September 2025, the Environment Agency carried out the first fish survey following project completion. They surveyed from the upstream edge of the gravel access point to just below the White Bridge – a stretch of about 100 metres. High numbers of minnow, and similar counts for stickleback and bullhead were recorded. Most significantly, however, they recorded 14 trout across a range of age classes. Habitat requirements change as trout enter different life stages, so the fact that a range of ages from juvenile to adult were recorded shows there is sufficient variety in habitat to support a healthy population.

The results from a macrophyte survey (aquatic plants growing in or near water), carried out shortly after project completion, were equally promising. The total number of recorded species had already increased from 18 at the old channel to 24 at the newly restored one. New species include celery-leaved buttercup, redshank, branched bur-reed and blunt fruited water starwort.

The Environment Agency will continue to monitor how the channel establishes over time. If you have any questions about the project, you can email the team at This email address is being protected from spambots. You need JavaScript enabled to view it. 

 

Project lead: Environment Agency

Project partners: Affinity Water, Dacorum Borough Council

Contact for more information: This email address is being protected from spambots. You need JavaScript enabled to view it.

Project start: 2015

Project end: 2025