A new Environment Agency weir on the River Lee at Amwell, near Ware, has been helping to boost brown trout populations and improve the wildlife of an internationally important nature reserve.
The weir has been placed at the southern end of Great Hardmead Lake, a former flooded gravel pit which forms part of Amwell Nature Reserve – which is renowned internationally due to the number of wintering water birds which visit it.
The lake, which is managed by the Hertfordshire and Middlesex Wildlife Trust (HMWT), is fed by several springs of high quality water which flow consistently throughout the year. The surplus water is discharged into the River Lee – a river popular with anglers for its brown trout.
In addition to the new weir, the discharge pipe from the lake has been moved 300m upstream – benefiting fish & invertebrates. Fifty tonnes of gravel has also been placed at the discharge point to create a spawning ‘riffle’, which will improve trout spawning success and overall habitat diversity.
The Environment Agency & HMWT worked together on the design of the weir – which consists of a small door, hinged at ground level, which can be raised or lowered via a gear controlled by a turn-key. This allows water levels to be controlled very precisely to provide just the right depth of water for ducks to feed.
Jim Seymour from the Environment Agency said: “The aim of this project was to conserve and improve the wild stocks of brown trout on the River Lee. As a result of a concentrated program of removing barriers to migration and habitat enhancement we have seen a tangible increase in the trout population.”
Tim Hill, Conservation Manager for the HMWT said, “The new weir will enable the Trust to set water levels in Amwell Nature Reserves to provide optimum conditions for wildlife throughout the year. During the winter we keep water levels high to provide for ducks but from late spring onwards the level is dropped to expose insect-rich muddy shorelines and provide shallow water which provides feeding ground for ducklings and wading birds as well as spawning habitat for fish.”
The project was a partnership between the Environment Agency, Amwell Magna Fishery, and Herts and Middlesex Wildlife Trust, in consultation with The Wild Trout Trust.