Parteen Weir: commentary and images

Here are some aerial photos and a video of Parteen Regulating Weir taken during July 2015. The headrace canal which transfers abstracted water to Ardnacrusha Hydroelectric Station is also featured. These images were taken using a Phantom 3 drone, which we have been using to survey the Lower River Shannon.

Parteen Regulating Weir controls the flow of water to Ardnacrusha Hydroelectric Station and to the Old River Shannon. The compensation flow provided to the old river is just 10 cubic meters per second (cumecs), which is equivalent to the natural 95 percentile flow (an extreme drought flow) in the river prior to the Shannon Scheme. The rest of the water from the River Shannon is diverted down the headrace canal to Ardnacrusha Hydroelectric Station.

This is not sustainable as it has destroyed the fisheries of the River Shannon, and the ecological status of the Lower River Shannon SAC

As well as being inadequate in terms of volume, the compensation flow is also a constant and unvaried flow that is only increased when Ardnacrusha Hydroelectric Station can no longer output the inflows into Lough Derg while operating at full capacity – 400 cumecs (e.g. extreme floods). In this situation ‘excess’ water is spilled though Parteen Regulating Weir. This can result in flows in the river abruptly increasing from 10 cumecs up to a few hundred cumecs – sometimes in a matter of hours – and reducing again in a relatively short time-scale. This can cause significant impacts on river, and for more information please see here.

Parteen Regulating weir is a major barrier to fish migration on the River Shannon. The fish pass is inadequate and the salmon hatchery at this site has also been a failure; despite the millions of fish released from here into the upper Shannon current salmon escapement into the Shannon upstream from here is less than 5% of its conservation escapement target.

PS: Comment on eel issues

In 2015 the ESB failed to get elver traps running in time for, what was widely acknowledged to be the largest elver run in 30 years. The ESB, their consultants and the “independent” “scientific” committee on eels have denied this, but we have the photos that speak for themselves and can prove that we took them when we said we did. The photos clearly show derelict traps.

The ESB upgraded a number of their elver traps this year – clearly in response to us embarrassing them. However, the elver trap at Parteen Regulating Weir is a tiny trap for such a large river, a token effort. Elvers will be attracted to the spillway here and most probably never find this trap. The spillway is used by some silver eels, but this usually gets just 10 cumecs compared with 400 cumecs going down the headrace to the turbines. During floods there are huge pressures of water going under this gate and there will be a significant passage mortality factor. The trap and transport programme for silver eels is really just a PR stunt with the sole aim of ensuring that there is no interference with ‘business as usual” hydroelectric generation. The silver eel escapement figures for the Shannon present in the “Independent” “Scientific” Committee Report are well and truly cooked!

Parteen elver trap
The new elver trap at Parteen weir. This was installed after we had exposed the ESB’s failure to meet their statutory obligations on the Shannon and Erne, in our opinion.

PPS: Parteen salmon hatchery should be closed

Parteen salmon hatchery should be closed. It has been a failure. How about replacing it with a rock ramp fish bypass channel running though it. The rock ramp would run though the area where the blue tanks in the hatchery are (see photo below) and arc around to join the reservoir just upstream of the dam. We would also need increased and variable flows for the old river, and fish diversion systems for the headrace and tailrace.

Parteen Regulating Weir and salmon hatchery. Room for a new fish pass to run though the hatchery?

This dam and its current management regime is not sustainable as it has destroyed the fisheries of the River Shannon, and the ecological status of the Lower River Shannon SAC. Something like this will have to be done, or we will be moving towards serious calls for dam removal on the River Shannon as is now happening in the USA.

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