A nature-like bypass channel was constructed in a floodplain of the River Loddon to facilitate fish migration around four permanent weir impoundments.
On the River Lodden at Arborfield, historic mill and weir structures prevented fish passage and had impounded the river for 4km upstream. A combination of civil engineering and soft engineering techniques were used to design and build a 200m weir bypass channel to reconnect 25km of the River Loddon.
The solution
Cain Bio Engineering created a step-down pool/riffle sequence using rock-ramps to manage the steeper gradient, they created gravel riffles to create streaming flows and fish spawning habitat. This created an immediate and easy passage for a wide variety of fish species while improving their habitat
This solution was selected as this is a sustainable alternative to hard engineered structures while creating durable nature like channels, encouraging the fish to pass freely in this steeper gradient. It’s also erosion free and flood-resistant immediately following construction.
