Flooding on Lower Shannon, December 2015

A selection of our photos of videos of flooding on the Lower (old) River Shannon during December 2015 is provided below. These were taken during early December when the ESB were spilling 375 cumecs of water down the old river channel. Shortly after taking these shots the ESB increased the volume of water being released from Parteen Regulating Weir to 440 cumecs. Click on any of the photos below to activate the gallery.

See the video below of Parteen Regulating Weir taken during December 2015 when the ESB were spilling 375 cumecs down the old river channel.

See the video below of the old River Shannon at the lower end of the Castleconnell Fishery (beat 6, the ‘Bush Hole’) taken during December 2015 when the ESB were spilling 375 cumecs from Parteen Regulating Weir.

See the video below of the old River Shannon at Castleconnell and Doonass taken during December 2015 when the ESB were spilling 375 cumecs from Parteen Regulating Weir.

We need to review the management of the Lower River Shannon in terms of water management, instream modifications and fish passage issues.

Sustainable water management

Since the Shannon scheme, the “old” River Shannon receives a compensation flow of 10 cumecs. This is equivalent to only a 1 in 50 year drought flow on the river prior to the construction of Parteen Regulating Weir. This has had a significant morphological impact on this river corridor. It is clear that there needs to be increased and variable flows in the Old River Shannon to be delivered within the context of a sustainable management plan for the Lower River Shannon. Spillages of water during flood events should also be tapered up and down slowly mimicking a natural hydrograph.

Removal of fisheries weirs and deflectors

The instream physical modification along the river would also need to be removed to restore the river back to a more natural physical state. Rather than enhancing the river’s ecology, the intrusive instream physical modifications on the Lower Shannon are working against the rivers natural fluvial geomorphological and ecological processes, increasing encroachment of vegetation, reducing the channel’s conveyance capacity, and preventing the water body from reaching good ecological status.

New fish passes and bypasses

Fish passage requirements on the Lower River Shannon also need to be reviewed. It is clear that new upstream fish passes and downstream bypasses are required for salmon, eels and lampreys. The River Shannon above Parteen Regulating Weir currently meets less than 5% of its salmon conservation escapement target. Traps to facilitate the upstream movements of juvenile eels are not operated regularly or efficiently. Thousands of downstream migrating silver eels and salmon smolts are killed each year in the turbines.  It is noteworthy that even at the peak of the floods and water spillages during December 2015 that turbine killed silver eels continued to turn up on the Lower River Shannon. Increased used of spillways and trap and transport will not solve this problem and silver eel (and salmon smolt) bypasses will have to be installed.

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