Improving the River Lea

Manor Road Park River Lea improvements - the challenge

 

The River Lea flows along the eastern edge of Manor Road Park in a deep, restricted channel. The riverbed is concrete and the river runs between concrete walls or steps with metal railings.

The way the river flows means that silt covers the natural gravels, making it harder for fish and other creatures to thrive. The high walls separate the river from the floodplain which can put other areas of the town at risk of flooding. Above all, the river is unwelcoming and hidden from the local communities who could be enjoying a rich natural environment.

How we improved the river

We worked with the Environment Agency and Luton Borough Council to agree on a proposal to improve the habitat and flow of the river, these included:

• To improve the biodiversity value of the river to support a better variety of plants and creatures in the water and on the river banks.
• To help the river stay healthy when water flows are low and reduce the local risk of flooding when flows are stronger.
• To make the river safer for everyone.
• To provide a pleasant and usable space for local people

What we've done

• Removed the concrete river bed and the concrete steps, tarmac path, concrete wall and metal railings;
• Make the river narrower and more winding
• Improved the riverbanks to give a stable slope to encourage a greater variety of plants on the bank and in the river and will not be at risk from erosion or collapse.
• Removed some overhanging branches from the large trees to allow more light to reach the river and encourage more plant growth in the river and at the water's edge.
• Re-connected the river to the surrounding environment by removing the concrete channel that confines the river along the edge of the park behind iron railings
• Re-located the children’s playground to create the space to meander the river through the park.

The project was completed earlier in Summer and the benefits of this work are now starting to take shape. Please see below for before and after photos.

The Moat Farm & Riddy Lane Allotment river improvement project was one of a number of projects that are taking place as part of the Revitalising Chalk Rivers partnership, in collaboration with the Environment Agency. These improvement works will help to restore and improve the habitat of chalk streams along the River Lea and rivers in other catchments.

 

Why did the allotment need to be improved?

The area where the river flows through the allotment gardens in Luton has been identified as a priority area for potential morphological mitigation works. The bank sides through this section are very steep, in places up to two metres deep, and are heavily shaded by trees and shrubs. The allotments themselves abut the river with no buffer margins, allotment plots have been extended into the riparian zone and used for storage of compost material, rubbish, and in some places the building of sheds. Some of the compost piles have collapsed into the river channel, which are a potentially serious source of pollution into the river.

 

Objectives:

• To naturalise the River Lea in Luton as much as possible;
• To improve biodiversity in the river corridor;
• To help the river meet the requirements of the Water Framework Directive;
• To make the river more resilient to low-flows;
• To carry out tree works to cut back overgrown trees and shrubs, to allow sunlight to reach the river and its banks.
• To re-instate a clear 3m riparian zone on the top of the river bank;
• To remove and dispose of the compost heaps on the river bank;
• To improve the river as an amenity feature for the allotment tenants;
• To reduce the risk of flooding

 

What we've done:

The Allotment Committee staked out a 3m riparian zone along both banks of the river. The allotment plot tenants were asked to remove any sheds and personal items within the 3m zone.

Following a phase one habitat survey, a detailed tree survey, reptile surveys and Water vole surveys, tree works (felling, coppicing and pollarding) and scrub clearance commenced. These works will let light into the river channel and encourage plants to grow in the river channel and on the river banks, creating new habitats for insects and fish.

The heaps of compost and rubbish on the edge of the river banks were removed and the riparian zone re-instated to ground level. Around 140 tonnes of compost and rubbish was cleared from the top of the river banks and removed off site.

Signs have been erected to remind tenants to keep the 3m riparian zone clear of compost and rubbish.

We will continue to monitor the river for morphological and ecological responses to the river restoration works.