Post by Hoppy on Aug 6, 2006 5:36:47 GMT -1
Environment Agency adopts ‘fish friendly’ approach to flood channel improvements on River Exe
Tiverton’s flood defence channel is getting an early makeover as the Environment Agency takes advantage of recent low river levels to carry out important maintenance and repairs.
By carrying out the work during a particularly dry spell the Agency is keeping disturbance of migrating salmon and sea trout to a minimum.
The concrete block lining of the flood channel is designed to allow as much water as possible to pass down the river at times of high flow. Every few years vegetation has to be cleared from the side of the channel to maintain flows and prevent the concrete blocks from being damaged by the roots of riverside trees such as alder and willow.
If left unchecked blocks can be dislodged during floods and the side of the channel eroded. Before the work commenced, biodiversity officers from the Agency carried out a vegetation survey to ensure only potentially damaging species are removed and that other riverside plants such as purple loosestrife are left unharmed.
Before commencing clearance work the Agency’s operations delivery team has reduced the level of the river still further by opening up a side channel around Tiverton’s Town Weir.
Great care was taken during this operation to prevent excessive disturbance of the riverbed. Levels of dissolved oxygen and suspended solids were carefully monitored to ensure any salmon and sea trout resting in pools downstream of the weir were not put at risk.
‘Upstream migration of salmon and sea trout is on hold at the moment with river levels so low. Our fisheries colleagues asked if we could take advantage of these conditions to complete the maintenance work at Tiverton ahead of schedule so as to minimise any disturbance to fish. We are happy to oblige,’ said Julian Brooke-Houghton for the Environment Agency.
Preliminary work started this week. The clearance of vegetation is expected to take approximately two weeks. The improvements also include the inspection and replacement of several non-return valves in the flood channel wall.
Tiverton’s flood defence channel is getting an early makeover as the Environment Agency takes advantage of recent low river levels to carry out important maintenance and repairs.
By carrying out the work during a particularly dry spell the Agency is keeping disturbance of migrating salmon and sea trout to a minimum.
The concrete block lining of the flood channel is designed to allow as much water as possible to pass down the river at times of high flow. Every few years vegetation has to be cleared from the side of the channel to maintain flows and prevent the concrete blocks from being damaged by the roots of riverside trees such as alder and willow.
If left unchecked blocks can be dislodged during floods and the side of the channel eroded. Before the work commenced, biodiversity officers from the Agency carried out a vegetation survey to ensure only potentially damaging species are removed and that other riverside plants such as purple loosestrife are left unharmed.
Before commencing clearance work the Agency’s operations delivery team has reduced the level of the river still further by opening up a side channel around Tiverton’s Town Weir.
Great care was taken during this operation to prevent excessive disturbance of the riverbed. Levels of dissolved oxygen and suspended solids were carefully monitored to ensure any salmon and sea trout resting in pools downstream of the weir were not put at risk.
‘Upstream migration of salmon and sea trout is on hold at the moment with river levels so low. Our fisheries colleagues asked if we could take advantage of these conditions to complete the maintenance work at Tiverton ahead of schedule so as to minimise any disturbance to fish. We are happy to oblige,’ said Julian Brooke-Houghton for the Environment Agency.
Preliminary work started this week. The clearance of vegetation is expected to take approximately two weeks. The improvements also include the inspection and replacement of several non-return valves in the flood channel wall.