“Chalk rivers should be protected or restored to a quality which sustains the high conservation value of their wildlife, healthy water supplies, recreation opportunities and their place in the character and cultural history of the landscape.”The State of England’s Chalk Rivers” World Wildlife Fund UK, 2014
A river runs through it
Anyone who walks through central Dartford’s bustling high street only has to turn right past the Museum to find Central Park – the town’s fantastic 26-acre green space with Acacia Hall just next door. The town and the park sit on the valley floor of the River Darent, which flows through the park on its way to the River Thames, approximately 2 miles downstream.
The River Darent is a chalk river – a rare and beautiful but heavily impacted freshwater habitat. Good quality, relatively unaltered chalk streams are characterised by cool, crystal clear, high-quality water filtered by underground chalk aquifers, with clean gravel beds and pockets of lush aquatic plants that provide important habitats for native fish (such as brown trout) and invertebrates.
The Darent is one of only 210 chalk streams in the world; 160 of these are in England.
The Darent is an important chalk river, a fundamental part of the regional landscape. Sadly the Darent today suffers from a legacy of modification by human activity. Former water mills, over-abstraction, polluted outfalls, flood risk prevention measures and weirs fragment this precious chalk stream habitat. These change the river from a continuous, free-running ecosystem into semi-isolated or “impounded” bodies of standing or slowly moving water. This physical impact completely alters chalk stream ecology, impeding the movement of many aquatic species and affecting water quality. Over-abstraction has had a significant impact on the Darent, and silt originates from urbanisation and agricultural practices. Bit by bit, as a fragmented river gradually silts up and loses its crystalline beauty, it runs the risk of becoming a forgotten backwater, a silty supermarket trolley repository.
The part of the Darent that runs through Central Park has been subject to heavy modification in the past. It has been widened to increase the capacity of the channel, and the weir prevents fish migration and impounds the upstream section of the river. Together, these result in siltation and degradation of the river habitat. The river’s flow in this channel has been impeded, and the flood relief channel has become the main watercourse.
Now, we’re working with Dartford Borough Council and the Environment Agency on the Acacia Hall/Central Park Restoration Project. The project will bring the Darent back into the heart of Central Park/Acacia Hall by removing the Acacia Hall weir and using flood risk neutral, nature-based methods and materials to reintroduce chalk stream river habitats and function. The Central Park/ Acacia Hall section of the Darent will flow again, allowing the public to spend time by a natural chalk stream with improved water quality and benefits to wildlife such as otter, brown trout, European eel and invertebrates.
Restoring the Darent in Central Park and Acacia Hall: how will it be done?
Our river restoration project will reintroduce natural features to the river, to create the type of variation in channel width and depth found in less disturbed river systems. These improvements will “kick-start” more natural, variable flow patterns – creating a greater variety of habitats that attract and support wildlife. Greater habitat diversity supports more resilient wildlife communities.
The natural features will be made from materials that naturally occur in river ecosystems, such as Large Woody Material, gravel and silt. Dartford Borough Council Parks Department has worked with the South East Rivers Trust and the Environment Agency to select trees in the Central Park area that will be felled to be used in the restoration project.
Many of the selected trees – which are being assessed to avoid disturbing any bat roosts – are damaged, hazardous to the public or are self-seeded sycamore. Sycamore is a fast-growing non-native tree species that out-competes many native tree and shrub species, and blocks out the sunlight to the river. A heavily shaded stretch of a river cannot sustain stands of aquatic plants or clear waters that support more diverse wildlife communities.
By opening up areas at selected sites in Central Park and Acacia Hall, the restoration project will create a mosaic of sunny and shaded spots for river habitats.
When will it be done?
The restoration work will start this summer as part of the Acacia Hall regeneration project. The creation of more natural banks, a more varied meandering river and improved marginal habitats throughout Central Park will allow everyone who visits it to experience more wildlife such as fish, birds and dragonflies.
To enable the work to take place safely in the channel, the water level will be lowered and flow will be diverted down the Flood Relief Channel to the east of Central Park, leaving a dry western channel to work in. This means that wildlife will not be harmed whilst the work takes place. All fish will be safely removed before the works commence. The restoration site will be fenced off during the works for public safety.
A vision for the Darent at Acacia Hall/Central Park
The vision driving the restoration of this section of the River Darent is to enhance the river channel through Dartford’s most valued urban green space, providing a focal point of natural aesthetics, amenity and wildlife habitats. The project will reconnect park users with the river, with possibilities for nature conservation, environmental volunteering and education opportunities. The new naturalised river channel will become a community resource, bringing biodiversity value in the heart of urban Dartford. The local community will benefit from these river improvements that will create an attractive environment where people want to be.