Dredging

Dredging is the process of removing built-up sediment, silt, and debris from the bottom of a waterway. It’s essential for keeping rivers, canals, lakes and ponds navigable, flood-resistant, and environmentally healthy. Without regular dredging, waterways can become blocked, shallow or polluted, affecting both boat traffic and ecosystems.

The Rothen Group works with Canal River Trust, the Environment Agency, and private waterway owners to dredge some of the UK’s most important canals and rivers. There are three main reasons for dredging:

• Navigation. Remove the accumulated silt and debris to ensure the waterway remains deep enough for vessels.

• Flood Risk Reduction. River dredging increases the capacity of a river, reducing the risk of localised flooding – especially after heavy rainfall.

• Preserving Ecosystems. Dredging maintains the ecological balance of waterways, improving water quality, and helping plants and animals to thrive.

Unfortunately, another common reason is the accumulation of litter and other waste. These materials degrade rivers and canals, making them dangerous to humans and animals.

Despite the basic principles of dredging remaining the same, canal and river dredging differ in a few specific ways. These include:

• River dredging typically targets deeper, faster-flowing water and often focuses on flood risk reduction and debris removal.

• Canal dredging, by contrast, usually involves shallower, slower-moving waters and focuses on maintaining safe navigation for boats, especially around moorings, winding holes and bridges.

Dredging a river presents numerous challenges. Digging a hole on land might be relatively simple, but removing material from the water is a technical and logistical nightmare.

The Rothen Group relies on our expert dredging specialists, who are experienced in using multiple types of dredging equipment. This includes floating dredgers, modular pontoons, and long-reach excavators. We even have specialist dredging barges that can access the deepest parts of a river. The process is laborious – the material is removed, dried, and then reused as topsoil or compost.

We also manage licensed disposal where reuse isn’t possible, ensuring environmental compliance. Every river dredging project is carefully planned to minimise disruption and maximise efficiency.

That depends on several factors, including the type of waterway, its usage, and how quickly sediment builds up. Busy canals, moorings, and marinas may require maintenance dredging every 1–3 years, while less active areas might only need it every 5–10 years.

Often, river and canal dredging is ignored for many years until it starts to become an issue. However, an example of proactive dredging is the River Thames, where the Port of London Authority routinely conducts dredging operations to ensure the river is safely navigable.