Backwater restoration in the Maidenhead to Teddington catchment

A backwater is a part of a river where the water is stagnant or flows slowly, often isolated from the main flow. These areas can be created naturally or artificially and typically occur in bends, oxbow lakes, or behind natural or man-made barriers.

Backwaters are characterised by:

• Slower water movement: Compared to the main river channel, backwaters have minimal flow, making them relatively calm.
• Habitat diversity: They provide unique habitats that support diverse aquatic life, including fish, macrophytes (aquatic plants), and macroinvertebrates.
• Nursery and spawning grounds: They serve as important nursery and spawning grounds for fish and other aquatic species.
• Ecological importance: Backwaters contribute to the overall health of a river ecosystem by offering refuge and foraging areas for wildlife, including critically endangered species, like the European eel.

Issues facing backwaters in the UK include:

• Pollution: agricultural runoff, urban wastewater, and industrial discharge contribute to the pollution of backwaters. This leads to poor water quality, which can harm aquatic life and disrupt ecosystems.

• Eutrophication: the accumulation of nutrients, particularly nitrogen and phosphorus, from agricultural fertilisers and sewage can cause algal blooms. These blooms deplete oxygen levels in the water, creating dead zones where aquatic life cannot survive.

• Hydrological alterations: Changes in water flow, due to damming, water extraction for agriculture and industry, and flood management practices can reduce the connectivity of backwaters with the main river. This impacts water exchange, habitat quality, and the overall health of these ecosystems.

• Sedimentation: increased sediment load from erosion and land-use changes can smother habitats, reduce water depth, and impact water quality.

• Lack of awareness and management: insufficient knowledge and lack of targeted conservation efforts can result in inadequate protection and management of backwaters.

Over the course of this project, Thames21 and project partners have assessed backwaters throughout the Maidenhead to Teddington catchment to identify opportunities for restoration. As part of this work, an interactive storymap was developed to bring together survey data, local knowledge, and ecological assessments, helping us pinpoint where restoration would deliver the greatest ecological benefit. The storymap was completed in March 2024 and can be found here:

Building on these findings, the project has now moved from assessment into delivery, with two priority backwaters selected for restoration. One has already been completed, and one is scheduled for early 2026.

Staines-upon-Thames (Delivered November 2025)

The first restoration was completed in Staines-upon-Thames in late 2025. Key improvements included:

• Replacing plastic nicospan (a fabric for riverbank protection) used for erosion control with natural hazel brash bundles, reducing pollution.
• Installing pre‑planted coir rolls containing yellow flag iris, purple loosestrife, and lesser pond sedge. These provide immediate marginal habitat in an area where steep banks previously prevented plant establishment.
• Coppicing dominant willow trees to increase light levels and support the growth of new marginal vegetation.

These interventions have already begun improving habitat structure and biodiversity within the backwater.

Windsor (Planned for February 2026)

The second restoration will take place in Windsor in early 2026. This project will:

• Reconnect a stagnant historic backwater to the main channel, improving flow, water quality, and fish refuge opportunities.
• Remove invasive bamboo from the backwater edge to prevent further spread and restore natural vegetation.
• Create a new marginal shelf to support native plant establishment and enhance habitat complexity.

This work will help bring a long‑neglected backwater back into the active river system, supporting a healthier and more resilient ecosystem.