The Office of Public Works (OPW) has launched an investigation into the “serious deterioration” of the recently constructed Bandon River fish pass and said “emergency works” will be carried out by the start of May.
Responding to concerns that the fish pass, involving a series of steps or a ‘rock ramp’ over a 130m stretch of the Bandon river, was falling apart, the OPW confirmed the river bed has been eroded but that urgent works will begin in a matter of days.
Ecologist William O'Connor, who was involved in the initial baseline survey for the Bandon flood relief scheme, had raised concern that the fish pass had "failed" and was blocking the migration of salmon, eels, and lampreys.
Irish Wildlife Trust campaign officer Padraic Fogarty also said flood relief schemes, such as the Bandon scheme, are “over-engineered" and that an entirely new approach is needed as well as reform of the Arterial Drainage Act.
The fish pass was designed by international experts, with input from national experts in the former Department of Environment, along with Inland Fisheries Ireland (IFI).
The OPW said it inspected the fish pass along with IFI representatives and a fisheries specialist who had worked on the project when it became aware in March that the river bed had deteriorated possibly due to "extreme flows" in the river in the previous month.
“The site inspections identified serious deterioration of the rock and gravel bed materials used in the construction of the fish pass, over its full length,” said the OPW in a statement.
“Of immediate concern is the erosion of bed material at the upstream end of the fish pass, which has resulted in the retaining wall, originally constructed below the bed level of the pass, becoming exposed and creating a ‘step’ up from the bed level immediately downstream of it.”
The situation has created “serious difficulties” for the migration of various species and urgent measures are needed, said the OPW.
“An Appropriate Assessment Screening process is already underway, in line with the requirements of the Habitats Directive, and is scheduled to be complete very shortly,” said the OPW, adding that large boulders, preferably natural, will be placed across the width of the fish pass to enable fish to migrate with greater ease.
“Subject to environmental approval, it is planned to commence the works in the coming days and to have all works completed before May 1 or shortly afterwards,” it said, adding that it will develop a longer-term solution over the next few months.