The River Ash in Ashford has been re-naturalised for the benefit of wildlife and people, learn more here about how these improvements are bedding in.
The Colne Valley Regional Park has worked with Spelthorne Council, The Environment Agency and Spelthorne Natural History Society to successfully re-naturalise the River Ash adjacent to Bronzefield Prison in Ashford. The project was designed and constructed by Five Rivers, a specialist river restoration contractor, in October 2020 which was the wettest October on record.
The project has enhanced over 0.5km of the river’s habitat for a range of aquatic wildlife, transforming the site to provide new habitats for fish, amphibians, invertebrates and waterfowl to thrive. Additionally, the River Ash was poorly connected to its natural floodplain which prevented it from expanding naturally at times when water levels rose. To reconnect the river and to restore some of the natural functions of the floodplain, we have installed two backwaters and a series of offline ponds.
A recently installed backwater, an important recruitment habitat and refuge for wetland species.
The River Ash Enhancement Project is complete and with some surprising changes resulted that we and Spelthorne Council have been working to understand.
Most notably, the pond to the south west of the HMP Bronzefield was continually dropping in level, to the extent that it almost dried out completely. The pond is fed via a pumped pipe and receives water from HMP Bronzefield. The pump had accidentally been turned off by the prison, meaning that the pond’s inlet was cut off, resulting in the wetland drying out. After some investigations the water is now regularly being fed back into the pond which is great news.
In addition, the anti-social behaviour which resulted in the he reeds being set on fire, is recovering with new reed growth emerging and the site is recovering.
The site has experienced prolonged flooding during 2021 which was unexpected. When the enhancement works were completed in 2020, which involved reconnecting the river to its floodplain via the creation of a series of ponds and backwaters, all features were functioning efficiently, and no flooding occurred. After investigation and monitoring of flood water levels, during the first half of 2021 we determined this is not correlated with the changes at the pond and is a spate issue. During our regular visits we found numerous man made dams which had been built into the river, these dams had been holding water back and impounding water upstream and pushing it into the flood plain. These dams were removed which reduced the flood waters and enabled free movement along the footpath.
However, the site is still experiencing flooding which is a surprise during the summer. This flooding correlates with high groundwater levels which is being experienced across the valley with numerous occurrences of flooding and saturated ground. This particular site is extremely sensitive to changes in groundwater level and used to be known as Ashford Wetlands and is a key part of the natural flood plain.
One of the aims of the River Ash enhancement project was to connect the river to it’s natural flood plain as the river had artificially been altered and straightened preventing it from expanding naturally when water levels r0se. Enabling the river to naturally flood into the area not only reduces flood risk downstream, but also brings wider benefits to wildlife providing a wet area and habitat encouraging increases in biodiversity.
With predictions regarding more variable weather conditions and changes in climatic conditions, flooding at this site may occur more regularly. After monitoring the site for 9 months with the council, we have identified where a boardwalk needs to be installed so that people can access the area year round. The council is working towards this with the EA, and after the permission is granted, we can move to the installation phase which is proposed for autumn this year.
The other river improvement works completed on site are unaffected and the enhancements to the river channel have established well, helping to create a naturally flowing river system with a range of flow types and water depths, providing great habitat for coarse fish, river flies and aquatic plant species. The areas disturbed by the construction of the project are also starting to become green with spring vegetation and with the fence line removed from the banks of the Ash, the river has now become a focal feature of the site.
In late spring a volunteer planting session with local residents was successful and we planted 640 plugs. A high proportion of these plants have survived and in a few years, should be big and established. There is another volunteer session sheduled for August to build dead hedges around the backwaters and ponds to protect them and reduce disturbance and protect the areas to enable them to establish and thrive.
If you would like to help out please sign up here: Volunteer Habitat Creation Ashford August 21
Berm and gravel riffle installation re-naturalising the rivers while also providing a range of flow types and water depths .