Extensive instream works and modifications have been placed along the Old River Shannon with the apparent aim of recreating salmon pools and to accommodate the reduced flows in this part of the river since the Shannon scheme. These wsorks commenced after the Shannon scheme, but most of the work was completed in the 1980’s and 1990’s.
These structures, comprising of hundreds of tonnes of rock and other materials, were placed in the river on an ad hoc basis by ESB Fisheries in the absence of any formal plan or Environment Impact Assessment. Many of these works were constructed in the river during the salmonid and lamprey spawning seasons causing severe ecological impacts at the time. Removal of extensive areas of priority Annex 1 alluvial woodland was also a significant feature of these instream construction works. These invasive structures remain as permanent features in the river today, and have significantly degraded the natural aesthetic character of the river and have reduced its ecological status.
Rather than enhancing the river’s ecology, many of these intrusive modifications are working against the rivers natural hydro geomorphological and ecological processes, increasing encroachment of vegetation, and therefore reducing the channel’s conveyance capacity
These ‘fisheries development works’ are designed for the 10 cumec compensation flow only and therefore render the fishery unfishable, and in many places inaccessible, at higher flows. These structures are therefore, in many cases, incompatible with the inevitable requirement to increase and vary the discharge in the river in the future. They also leave Castleconnell being perhaps the only fishery in the western Europe which becomes unfishable when there is even a slight water rise.
Rather than enhancing the river’s ecology, many of these intrusive modifications are working against the rivers natural hydro-geomorphological and ecological processes, increasing encroachment of vegetation, and therefore reducing the channel’s conveyance capacity. They have increased flood risk on the river, and are probably contributing to the high water levels in the river during flood events (e.g. November 2009) as the river channel can no longer cope with increased flows (as a result of direct and indirect effects of placing these structures in the river).
It is also noteworthy that many of these structures have also not been successful in their original purpose of improving the fishery. In some respects these have created a ‘runway’ for salmon with salmon now quickly passing through the fishery to end up below Parteen weir. Many of the pools created no longer hold salmon, even at the peak of the summer runs.
The ORSRG is campaigning to get many of these structures removed or realigned in the river to restore a more naturalised river character which is more appropriate for a Special Area of Conservation and the management of the river within the requirements of the Habitats and Water Framework Directives.
The photos above of the ‘wall’ that was built along the middle of the river channel in beat 5 in the 1990’s is one of the more extreme examples of these modifications. We will be campaigning to have these and other structures removed, breached or realigned to restore a more natural looking and functioning river.
The photo below shows the car park at the entrance to Beat 6 at the Castleconnell Fishery under water during early January 2014. The flooded entrance to a recently constructed house, arguably built too close to the river, is also apparent. The flows (discharge) in the river at that time would be considered just average flow volumes prior to the Shannon scheme. The water levels are higher than they should be due to channel encroachment by trees and other vegetation, siltation and also due to the presence of numerous instream ‘fisheries development’ structures. The conveyance capacity of the river channel has been significantly reduced due to these effects, flood risk has been increased, and the ecological status of the river has been diminished.
The encroachment of silt and vegetation has mainly occurred as a result of the long term severe reduction of discharge in the river (compensation flow is equivalent to a 1 in 50 year drought flow only) which has reduced the ability of the river to maintain itself through natural hydro-geomorphological processes. However, the effects of encroachment have been exacerbated by the numerous ‘fisheries development’ structures in the river.
For further information please see these posts:
- A sustainable compensation flow is needed for the Old River Shannon
- Then and now; The “bush hole” area of the Castleconnell Fishery on the Lower River Shannon
The ORSRG is campaigning for the provision of increased and variable flows in the Old River Shannon to be delivered within the context of a sustainable management plan for the river and SAC. We will also be campaigning for the removal of many of the fisheries weirs and angling structures in the river, to facilitate the restoration of a physically more naturalised river corridor in the interests of complying with the requirements of the Water Framework and Habitats Directives.