'Death by a thousand cuts': Hydropower killing, injuring and trapping fish by the tonne

Noteworthy investigates barriers along the River Shannon as deaths recorded at ESB stations and salmon hatcheries.

By Anthea Lacchia

Design for SHALL NOT PASS project featuring a salmon leaping in the air with a large dam in the background.

EELS HAVE “AN incredible story to tell” but it is being cut short by manmade barriers on the River Shannon.

Critically endangered European Eels start their lives over 6,500km away, near Bermuda in the Sargasso Sea, then float along ocean currents until they finally hit European rivers, where they live for 10 to 20 years.

But when they arrive in Ireland and try to swim up the River Shannon, they are met with multiple barriers, including hydroelectric dams and weirs, which hinder their movements both up and down the river.

Once those who make it upstream are ready to return back to the Sargasso Sea to spawn, they are again met with barriers. This time they include turbines that can kill and injure.

This results in “severe internal injuries” or in the eels being “severed” by the blades, ecologist Dr Will O’Connor of Ecofact Environmental Consultants told Noteworthy. O’Connor used to work for the ESB in the 1990s and has conducted research on migratory fish including eels.

The ecologist has been highlighting the negative impacts of the Shannon hydroelectric scheme on fish, water and the environment for more than 10 years. He and many other experts we spoke to are growing increasingly frustrated with the lack of progress on addressing these issues in the Shannon.

O’Connor wearing dark trousers and top hunkering on the side of the river holding a dead eel with both hands. A number of dead eels are also lying in front of him on the river bank. A small boat and rainbow can be seen in the background. Dr Will O'Connor holding dead eels below the Shannon hydroelectric scheme.
Source: Dr Will O'Connor/Ecofact

Over the past four months, as part of our SHALL NOT PASS project, our team has investigated this issue and can now reveal:

  • Fish, including critically endangered eels and protected species such as salmon, trout and lamprey, are dying, getting injured or becoming trapped by barriers along the River Shannon, with large numbers of deaths recorded at ESB hydroelectric stations and salmon hatcheries
  • Fish passes along many Irish rivers are not fit for purpose, according to experts who are calling for improved fish passage and removal of obsolete structures
  • Huge declines in fish stocks have occurred over the last century but no fish data was recorded by the ESB for over two years up to mid-2022 due to fish counters malfunctioning
  • Ecologists and community members are lamenting decades of government and ESB inaction when it comes to tackling the environmental impacts of the Shannon ESB hydroelectric scheme and are critical of the existing mitigation measures
  • No environmental impact assessments were conducted by ESB for its Shannon and Erne schemes in 2021 or 2022

PDF version available here>>

This investigation involved dozens of interviews with scientists, campaigners, NGOs, ESB staff, anglers and community groups, as well as visits to key locations along the Shannon and dozens of Access to Information on the Environment (AIE) requests.

Part two delves into concerns over “unsustainable” levels of water abstraction in the river. You can also explore the key issues by listening to The Explainer x Noteworthy podcast on this project:

The Explainer · By Noteworthy: What is the environmental cost of hydropower?

‘Immediate effect’ of the Shannon Scheme

Six river catchments in Ireland have major hydropower stations at their lower ends, with the largest being Ardnacrusha on the Shannon. The lower stretches of the Shannon were heavily modified in the 1920s by this dam and station.

When it was built, the station, with 86 MW capacity, met the electricity needs of the whole of Ireland. Today, Ardnacrusha represents around 2% of ESB’s installed capacity, supplying electricity to about 46,000 homes.

ESB recently announced its plans to invest “more than €1 billion a year up to 2030″ – mainly focusing on solar and wind – to help Ireland meet its 2050 net-zero energy targets. Hydropower doesn’t feature in this plan. It may be renewable, but it also comes with a high environmental cost.

In 2014, about 300,000 young eels died at ESB’s Cathaleen’s Fall dam in the Erne hydropower scheme, in a major fish kill that was investigated by Inland Fisheries Ireland (IFI), though no prosecutions were sought.

In the Shannon Scheme, critically endangered eels, as well as protected fish species such as salmon, trout and lamprey, are being killed, injured and trapped. This issue has been known since at least 1935, when a Dáil debate drew attention to an “abundance of salmon imprisoned” at Ardnacrusha’s tailrace.

While most sources Noteworthy spoke to did not suggest the dam and hydroelectric scheme should be removed, they were critical of the mitigation in place when it comes to environmental impacts.

  • Noteworthy, the crowdfunded community-led investigative platform from The Journal, supports independent and impactful public interest journalism.

Up until the 1920s, there were “huge” numbers of salmon in the Shannon but the scheme had “an immediate effect on fish migration”, according to a 2021 report from the Department of Housing, Local Government and Heritage (DHLGH), released to Noteworthy via AIE.

Fish are clearly “having difficulties migrating upstream and passing over the Shannon Scheme structures to reach their spawning grounds and other habitats upstream”, the report found.

Salmon numbers moving up the Shannon scheme have declined from around 9,000 in the 1970s to about 1,000 in the last decade, according to ESB data. The ESB “controls the fishing rights of the entire River Shannon”, with maintenance and preservation of fishery resources undertaken by its conservation team.

Salmon are not alone in this decline. Eels returning to Europe’s rivers have dropped 95% since the 1980s. In Ireland, nearly half of the freshwater habitat for eels is above hydropower dams.

That decline is “all down to habitat loss”, said Andrew Kerr, chair of the Sustainable Eel Group, a European-wide conservation organisation.

“A great big barrier across the biggest river in Ireland, and really low down, cancels out so much habitat. It’s not surprising that the population has collapsed. You’re squeezing the life out of the system.”

Kerr said that “of course we want hydropower”, but the environment needs to be factored into any “calculation”. “Ireland is a tragedy for eel,” he added. There are “lots of good intended policies, but I’m not sure that they are effective”.

‘Fragmented river landscape’

Across Europe, there are over 1.2 million barriers in rivers, according to a recent study by AMBER, an EU-funded project.

Europe is “probably the most fragmented river landscape in the world,” said Carlos Garcia de Leaniz, AMBER project coordinator and aquatic biosciences professor at Swansea University in Wales.

“In Europe, more than 90% of the barriers are not dams,” he told Noteworthy. “What is really damaging and fragmenting is not a few large dams, but thousands and thousands of small barriers. About 15% of the barriers that we have surveyed are obsolete.”

Brian Coghlan, IFI research officer, also said that small structures such as culverts that channel water can have a big impact. It’s like “death by a thousand cuts”.

IFI is creating an inventory of barriers as part of its National Barriers Programme. This received over €785,000 from the DHLGH from 2017 to 2022, with 2023 funding “yet to be allocated” as of mid-February, according to AIE requests to IFI and the Department.

The first step is to assess where the barriers are, said Coghlan, then what they are and “what can we do about them when we don’t have very much money. It comes down to prioritisation.”

To date, IFI have identified just over 73,000 possible barriers, with around 43,000 still to be examined. Of those that have been looked at, 7,500 were identified as potential barriers. A breakdown of these and IFI’s progress can be viewed here>

National Barrier Programme funding is “not for barrier mitigation”, an IFI spokesperson told Noteworthy. Only five barriers had this work done by IFI over the past six years, with 13 planned for the future, including two marked for “barrier removal”, according to an AIE response.

IFI “may have been involved in more barrier mitigation with funding from other agencies”, but could not confirm this.

“I would hope that funding becomes more readily available for actual mitigation, and that, under the Water Framework Directive, headcount can be found to hire people to just do this,” said Coghlan.

Infographic depicting 100 fish passing over a ladder marked 30%, resulting in 30 fish, which then pass over another ladder marked 30%, resulting in nine fish at the end. Fish passage across fish passes that are 30% effective.
Source: Noteworthy

Where removal of a barrier is not possible, fish passes can be used. These come in different shapes, such as a series of steps that look like a ladder, or a ramp with rocks or bristles.

“Fish passes are better than nothing,” Kerr told Noteworthy, but added that they don’t solve the problem.

Even a “really good” fish pass is around 30% effective, he explained, meaning only 30 out of 100 fish can travel over it. Adding a second barrier and pass, those 30 fish now reduce to less than 10, with some rivers having “many, many, many of these barriers”.

Our SHALL NOT PASS investigation examined some of the major obstacles along the Shannon that fish encounter. First up, the biggest of them all:

Barrier - Ardnacrusha. With symbols indicating a dam, turbines and turbulence.

Ardnacrusha station consists of a large building with a grey roof in front with a dam which rises above it behind. Water is rushing down the spillway to the right of the dam. The river looks calmer behind the dam with turbulence visible in front. Ardnacrusha, ESB's first hydro station, was commissioned in 1929.
Source: Dr Will O'Connor/Ecofact

Ardnacrusha was ESB’s first hydro station, commissioned in 1929, and is supplied with water from a headrace canal originating over 12 km upstream at Parteen Weir. Discharge water from the station flows almost 2.5 km along a tailrace canal before meeting the original River Shannon near Limerick City.

Migrating fish, such as baby eels (called elvers) or adult salmon, can either go up the original Shannon or swim into the tailrace. However, discharge from the station attracts them into the tailrace, as fish are attracted to large volumes of flowing water.

What awaits at the station is a dam with four turbines that each can deliver about 100 tonnes of water per second, a 30-metre high spillway, through which surplus water is spilled downstream, and a boat lock.

ESB staff told Noteworthy during a field visit that there are a number of specific measures aimed to help counteract these serious obstacles.

These include a fish pass in the shape of a cylindrical lift retrofitted in 1959, and elver traps – ramps fitted with brush-like bristles for eels to climb on before they are put in a box and moved upstream of the dam. For this ‘trap and transport’ of eels, the ESB employs former eel fishermen.

“We take our fisheries conservation responsibilities seriously,” said Tom Moran, community relations and fisheries manager with ESB.

“We do acknowledge that hydro generation on the rivers does result in fish mortality. Our focus is to try and minimise those as best we can and to maximise the survival rates of all the fish that are migrating up and down the rivers.”

Map of the Shannon with markers for each of the barriers Noteworthy examined. Symbols depict various types of impacts on fish including: Fish deaths, dam or weir, fish pass issues, trap and transport, turbines, turbulence and water diversion.

Turbulent waters and ‘horrific injuries’

When Noteworthy visited the Shannon in December, turbulent water was flowing down the spillway while one of the turbines was being refurbished. O’Connor told us that river lampreys and salmon were likely becoming trapped and exposed to supersaturated waters at the base of the station.

Gas supersaturation leads to bubbles in the water. Nitrogen bubbles form inside the fish “like a diver getting the bends”, he said.

“In the chaos”, it’s absolutely impossible for the fish to go upstream. It would be impossible for any fish to find the fish pass, according to ecologist Dr Will O’Connor.

At the same time, critically endangered silver eels trying to migrate downstream along the canal either go through the turbines or down the 30 metre-high spillway.

“There are no specific fish protection facilities or downstream fishways (e.g. bypasses) in place” at Ardnacrusha Station, as noted in the final report commissioned by the Department in 2021 and released via AIE.

At least one in five eels die going through turbines at the station – this was equivalent to 1 tonne of eels in 2021, according to ESB’s 2021 annual report.

But this is an underestimate, given the number that are injured and fall victims to predation after passage, according to many of the experts we spoke to.

Big female eels carry millions of eggs that are “important for the future of the species” and “every female eel will be compromised. They will hit the runner blades, the sides of the turbines, they will have those pressure shocks, come out disorientated and are easy to see by predators,” said O’Connor.

View from the top of the dam at Ardnacrusha with large pipes coming down from it in the foreground and turbulent water seen at the bottom. Turbulent water spilled from Ardnacrusha during our visit earlier this year.
Source: Alice Chambers/Noteworthy

A major fish kill occurred during Storm Barra on the night of 7 December 2021, according to the ecologist. On 8 December, he found hundreds of adult eels dead and dying downstream of Ardnacrusha, which indicated that it is likely that thousands died.

Dr Dennis Doherty, fisheries biologist with ESB, said that the IFI investigation “did not find any damaged or dead eels downstream”. He added: “We do take criticism on board and we do our best in terms of fisheries conservation.”

IFI’s investigation - conducted on foot on 9 December as a boat was unable to be launched “due to weather constraints” and by boat the following day – recovered just one dead eel.

This investigation stated that there is “no doubt that the turbines at Ardnacrusha are causing mortalities of eels at an estimated rate of 21%” but “IFI does not have a role in regulating the operations of the ESB at Ardnacrusha”.

“IFI would welcome a review of the flow and turbine operations around the time of peak silver eels migration to reduce the mortality levels and improve fish passage via the old Shannon channel,” it concluded.

Though both turbines are damaging, the kinds of injuries eels get depend on the type of turbine they go through. There is one Kaplan (1934) and three Francis (1929) turbo-generators at the station.

The Francis turbines can cause shocks as “eels hit off the blades” and injuries from severe pressure changes, according to O’Connor.

“A lot of them have their eyes bulging out.” O’Connor said that ”most eels in the last few years are fully intact, there is no external evidence of damage, but they have severe internal injuries”.

If eels go through the Kaplan turbine, which has moveable blades, they are severed. “The blades cut them in half and you get these horrific injuries,” the ecologist said.

Dead eels lying on grass. O’Connor - whose arms and legs are only visible - is bending over them, holding one of the eels. Dead eels after Storm Barra in 2021.
Source: Dr Will O'Connor/Ecofact

The 21.5% mortality rate is inaccurate, O’Connor explained, because it does not take into account dead or injured fish that float downstream and would be read as alive by the tag studies as “any eel moving past… was assessed as a live eel”.

Noteworthy asked ESB for a comment on this and whether they are going to revise the mortality estimates. A spokesperson said that eels take both the old Shannon and Ardnacrusha routes downstream but the “one in five eels quote is only for those eel that go through Ardnacrusha”.

They added that the number of eels escaping to sea are therefore “higher” as “eel take both downstream routes according to flow rates”. The estimates were undertaken independently by NUI Galway, with the results “peer reviewed within several scientific publications”.

“ESB is open to revising these Ardnacrusha route figures but only when there is a change in the downstream passage turbines route or if there is a better technological way of producing these estimates,” they added.

‘Smolt blender’

When it comes to salmon, the Kaplan turbine is known locally as the “smolt blender”, O’Connor told Noteworthy.

This is because smolts – salmon that are one year old or more – are run through the Kaplan turbine as part of ESB’s smolt generation protocol, one of its mitigation measures to facilitate downstream migration.

The smolt generation protocol, which runs from St Patrick’s Day to the middle of June, aims to get any salmon smolts that are up above the station to below the station “as fast as possible and as safely as possible”, explained ESB’s Doherty.

During this period, the Kaplan turbine is turned on at full load, where the gap between the blades is highest, at dusk and dawn periods to try and get the fish down the system, he said.

“What you don’t want is turbines to be off and for large numbers of shoaling fish to be hanging around for weeks and weeks,” because they will be stressed out and will be subjected to fungal disease and predation, he added.

However, smolts die as they move through the turbine. In their annual reports, ESB said the survival rate for salmon smolts during the smolt generation protocol is 89.4%, though many sources believe much lower numbers of salmon actually survive.

Castleconnell - marked on the Lower Shannon River.

Four volunteers wading through a shallow river with rakes. Trees with autumn-coloured leaves hang overhead. Pat O'Connor and volunteers raking to remove silt for salmon to spawn.
Source: Castleconnell River Association

On the original river Shannon, which is a special area of conservation (SAC), locals have seen “huge changes” since the hydro scheme, according to Pat O’Connor, chair of the Castleconnell River Association. This organisation works to restore fish habitat and remove invasive species in the original river.

In 2006, when the association was formed, out of 22 locations that used to be spawning areas where eggs are laid and nursery areas where young fish live, only two were still active, which was “absolutely disastrous”, he said.

Changes include much lower water levels, increased sedimentation and vegetation, loss of habitat for fish to spawn and grow, and decline in fish numbers.

Much of the organisation’s work involves ensuring light and clean sediment are present, he explained. And results are visible, with the number of salmon nests – called redds – increasing from 105 in 2008 to 452 in 2020.

This area used to be so famous for salmon, Pat O’Connor told Noteworthy. But now a “critical number” of salmon is lost through the hydropower scheme, he added. “We want to at least try and preserve the pieces that are hanging on.”

One of the major issues, according to experts, is that excessive water is being diverted towards the dam and away from the original river.

  • Tomorrow, in part two of our SHALL NOT PASS investigation, we delve into concerns over “unsustainable” levels of water abstraction in the river.

“If the Ardnacrusha was going through planning today, there is no way it would get permission because of the Habitats Directive and Water Framework Directive,” said Dr Elaine McGoff, Natural Environment Officer with An Taisce.

Not only can dams and weirs “prove really detrimental to migrating fish”, she added, but they also “really change” the sediment “dynamics in the river”.

Natura 2000 is a network of core breeding and resting sites for rare and threatened species across the EU. 

An Appropriate Assessment (AA) is a focused impact assessment on whether a project or development will likely affect the integrity of a Natura 2000 site “in view of its conservation objects”, with screenings the first step.

Any potential adverse effects are then examined and presented in a Natura Impact Statement (NIS).

In our AIE request to ESB, we asked for all environmental impact assessments for 2021 and 2022 for the Shannon and Erne Schemes.

Only two screenings, which mostly ruled out any adverse impacts of the works in question, were done. One was for vegetation clearance works, another covered 14 different river works – some of which mention the need for a pre-works survey by an ecologist. No Natura Impact Statements or Appropriate Assessments were returned.

Barrier - Parteen. With symbols indicating a weir and diversion of water.

Parteen weir - a large structure that spans Parteen Reservoir. In front of the weir are two channels of water where the river is split into a canal and the original river. Aerial view of Parteen, showing the water being diverted.
Source: Dr Will O'Connor/Ecofact

The next obstacle for fish is the weir at Parteen, part of ESB’s Shannon hydroelectric scheme. Noteworthy visited this site, where the original river Shannon splits off and is diverted to Ardnacrusha station downstream.

During the 2020/21 season, an estimated 13% of eels from Killaloe migrated downstream via the original river Shannon, according to a 2020 technical group report.

As part of existing mitigation measures to improve passage, there is a fish pass, built in 1929 when the station was built, with a series of pools which fish travel across, and three elver traps, where eels are captured and moved upstream at certain times of the year.

When it comes to downstream passage, similarly to Ardnacrusha, there are no fish protection facilities or fish passes at Parteen Weir.

“Neither fishway meets modern best practice and [they] do not facilitate multi-fish species passage as required by the EU Water Framework Directive (WFD),” the 2021 Department-commissioned report found.

Fish pass made up of concrete and metal structures with steps down with water running over them. A sign says: Danger - Deep Water. Fish pass at Parteen weir.
Source: Alice Chambers/Noteworthy

A ‘two-year-plus’ fish counter malfunction

The ESB normally records fish migrating through their fish passes by using fish counters.

However, a malfunction across all fish counters in all ESB hydro schemes from 2020 to mid-2022 led to no fish being counted during that time. Doherty told Noteworthy that it was due to staffing issues during the Covid pandemic.

“We’ve had a two-year-plus hiatus” during Covid, said Doherty. “At each site location only core staff could go into the sites… We weren’t counting the fish, but the fish passes were open and fully operational,” he said.

The counters at Ardnacrusha and Parteen Weir were reinstalled in 2022 and are now operational, according to the ESB.

Noteworthy obtained fish census activity for 2022 through an AIE request. This is now undertaken by IFI independently of ESB.

‘Not as effective’ as previously thought

Parteen is also the location of an ESB salmon hatchery, built in 1959 and used to “assist the recovery of wild salmon” upstream of the scheme.

Each year, about 90,000 fin-clipped smolts are released from the hatchery as part of a programme run in collaboration with the Marine Institute, with some returning as adults.

“The proportion that return gives a very good indication of marine survival which is only 1% or 2%,” said Doherty. In contrast, there used to be a 40% return rate in the 1960s, but pressures at sea, including lack of food, have caused numbers to decline, he said.

This is one of three salmon hatcheries operated by ESB, with the others on the Lee and the Erne. Experts we spoke to expressed concern that hatcheries in general are not considered effective in conservation.

Dr Ronan O’Sullivan, ecologist at the University of Helsinki, is co-lead author on a recent study which found that, across their lifecycle, captive-bred Atlantic salmon introduced into the wild contribute fewer offspring to the next generation compared to wild fish.

A large number of orange-coloured fish eggs lying at the bottom of two tanks of water. A hand of an ESB worker is touching the top of the tanks. Salmon eggs at Parteen hatchery during the visit by Noteworthy.
Source: Alice Chambers/Noteworthy

Overall, hatcheries are not as effective in conservation as people thought when this practice started about 200 years ago, O’Sullivan told Noteworthy, adding that they “shouldn’t be seen as a panacea for declining populations” and may be needed for reasons such as rural employment.

However, “if you’re continuing to degrade the river environment, there’s no point having a hatchery on it”, he said, as “you’re never going to get a self-sustaining population”. 

When it comes to effects on wild populations, an ESB spokesperson said that given that UCC research has shown that “existing Shannon salmon populations are a hatchery-based population of fish… the continued release of hatchery salmon will have no consequential effect”.

Death of 100,000 salmon

A major fish kill took place in the hatchery at Parteen on 30 April 2022, when just under 100,000 out of 120,000 salmon – 83% of the stock – died in its tanks.

We asked ESB how this happened during our field visit to Parteen and Moran said it was “an algal bloom”.

This was what a vet’s assessment 10 days after the kill event stated was “most likely”, having found a type of algae on the gills and stomachs of the remaining fish. Noteworthy obtained a copy of the full third-party investigation report via an AIE request to the ESB.

“That was a big shock to the system… We are currently implementing all the recommendations arising out of that report,” Moran said.

We asked the ESB about the number of staff working at that time and a spokesperson told us that the hatchery manager “was rostered for the weekend of the fish kill”.

Killaloe. With symbol indicating trap and transport of eels.

Old stone bridge over a wide river covered in climbing plants with traffic driving over it. In front is a metal structure with some nets hanging from it on one side. Nets in the river at Killaloe weir.
Source: Anthea Lacchia/Noteworthy

Killaloe is 18 km upstream of Ardnacrusha dam and one of the locations where ESB operates its trap and transport programme for eels.

Here, ESB employs a contractor to trap downstream migrating adult eels in nets. The eels are then moved down from the weir at night during their period of migration. From here, they end up in the Kilmastulla River which flows into the original River Shannon.

Only about 30% of eels migrating downstream in winter are captured by nets, according to ESB annual reports. They are caught at three sites – the other two are at Athlone.

ESB staff told Noteworthy they are increasing the time they are operating trap and transport of eels. It will now be done from early August until February, instead of from September to December.

O’Connor expressed concerns over the number of nights the nets are put down “even during peak migration periods”.

We analysed net data, from information obtained via AIE, and found that there were a large number of nights when nets were not put down over the past two years during migration periods.

There are also concerns over the handling of the eels.

Kerr of the Sustainable Eel Group said that eels have very small scales and a thick mucous membrane to shield it from pathogens. “If you scrape a patch of mucus off the eel as it goes through, you let the bugs in and eels die slowly from that process,” he said.

Barrier - Meelick. With symbols indicating a weir and fish pass issues.

Past Lough Derg but before the old crossing point at Shannonbridge, fish encounter Meelick weir, built in the 1800s but damaged by storms in the past 15 years.

Since then, a 300m-long steel walkway was built across the weir as part of a €3.2 million rehabilitation project by Waterways Ireland (WI).

The intention in the planning application was to “sensitively restore the weir to its original condition”, said Dr Will O’Connor who prepared the Natura Impact Statement (NIS) and Environmental Impact Statement (EIS) on behalf of WI.

The NIS, seen by Noteworthy, states that eel passes were “to be provided at four locations to facilitate upstream passage over the weir”, as well as otter ledges.

However, no otter ledges were provided and only two eel passes were fitted retrospectively, and, according to O’Connor they were not functioning when he visited the site in February 2022.

They built “a different project than was assessed” in the EIS/NIS, said O’Connor, adding that a new fish pass should have been put in as well.

A WI spokesperson told Noteworthy that “the design and specification of the two pumped eel passes was completed and installed during the construction phase with input from UK fisheries consultants and IFI”.

Another type of pass – baffle eel passes – “were installed within the weir on either side of the existing fish pass” according to the team. This was “following agreement with” IFI “as this was considered a suitable beneficial location for eel passage in accordance with planning requirements”.

The spokesperson said that it “is actively engaged” with the National Parks and Wildlife Service (NPWS) “in relation to the design and installation of otter ledges on either side of the weir”, and is committed to delivering them by “Q4 2023″.

Barrier - Athlone. With symbols indicating a weir, fish pass issues as well as trap and transport of eels.

Before Lough Ree, another barrier lies ahead at Athlone – a weir with a small fish pass as well as another of ESB’s trap and transport locations for eels.

“Most fish get over Athlone weir, but not through the fish pass,” said ecologist O’Connor.

“When the river is high, it’s such a small little thing they don’t find it. They go over the weir, over the sides of the weir, or under the gates.”

We asked WI whether it has any plans to improve fish passage. A spokesperson said that “proposals will be subject to detailed environmental assessment, consultation and full planning applications in due course”.

Barrier - Tarmonbarry. With symbols indicating a weir and fish pass issues.

A large structure across a river made of metal that appears to be rusted as well as concrete. A gap is on the right with steps behind. Fish pass at Tarmonbarry Weir.
Source: James Naughton

Over 150 km upstream of Limerick City, the next major barrier is a weir at Tarmonbarry, on the border of Longford and Roscommon. The current fish pass at this weir is not functional, James Naughton, angler and secretary of the Lough Ree Angling Federation, told Noteworthy.

The issue has been known for over 20 years, with a 2010 article in the Longford Leader describing “concerns for salmon trapped at Tarmonbarry” and plans for a new fish pass. Despite this, there has been no action to date, said Naughton.

This type of fish pass can’t work for eels or lamprey because they can’t jump, according to Ecofact’s O’Connor, with coarse fish, such as bream and rudd, not strong enough swimmers.

It could potentially work for trout and salmon, but there isn’t enough water in it, he explained, adding that it’s a “horrendous design”.

IFI acknowledged that Tarmonbarry weir “remains a significant barrier to fish movement”, in a letter Naughton received in April 2022, seen by Noteworthy. However, the agency stated that Waterways Ireland (WI) had informed it that “the project is under review due to the very significant cost implications”.

When we asked WI what actions are planned, a spokesperson said that “proposals will be subject to detailed environmental assessment, consultation and full planning applications in due course”.

Barrier - Ballintra. With symbols indicating a weir and fish pass issues.

Weir on a river made of concrete with concrete steps in the foreground with gaps in between. Photos (above and below) supplied by the ESB of Ballintra fish pass.
Source: ESB

Almost at the last of the main lakes on the Shannon, Lough Allen, another barrier awaits. Ballintra is an ESB weir consisting of sluice gates, “an absolute barrier”, according to O’Connor, who doesn’t “think any fish can get through”.

However, a spokesperson for ESB sent Noteworthy photos of the fish pass and said that it “is working as normal” with “both upper and lower gates” open.

But the presence of water in a fish pass does not mean it is working and fish are using it, cautioned O’Connor.

A channel made of concrete with walls of varying heights, also made of concrete, with water inside, with a gap between the top of the walls and the water.

Barrier - Annacotty. With symbols indicating a weir and fish pass issues.

In addition to migrating along the Shannon, fish swim up its tributaries such as the Mulkear River. On that route, Annacotty weir awaits just upstream of Limerick City.

This has been classified as a “significant barrier” to fish by IFI. The weir, which lies within the Lower River Shannon SAC, is the subject of an ongoing fish passage project by the state agency, with nearly €100,000 in funding.

TD Malcolm Noonan, Minister of State for Heritage, told Noteworthy that, as part of the IFI project, the weir “has been identified as a priority for mitigation works” and “feasibility studies are underway to identify the preferred option”. He added that “IFI expects to complete these works in 2025”.

According to a 2021 IFI assessment, released via AIE, this is a “high impact barrier” for adult salmonids (a family including trout and salmon), and a “complete barrier” to adult lamprey, juvenile salmonids and cyprinids (a family including carp and minnow).

The report mentions issues with existing fish passes at the weir, as well as fast, highly turbulent waters which hinder upstream fish migration.

A petition by O’Connor asking the Office of Public Works (OPW), IFI and Limerick City and County Council to remove or lower the weir and install a rock ramp fish pass, has gathered over 10,500 signatures.

The weir is ornamental, with no purpose, and the main species affected are river lampreys and sea lampreys, said O’Connor.

‘Roadmap developed’ but locals frustrated

When it comes to the lower Shannon, Minister Noonan said that, “a roadmap has been developed, which sets out a programme of initial investment measures to make a significant improvement to free passage for fish at Ardnacrusha and Parteen Weir in the short-term.

“It also provides the platform for long-term enhancement of the ecology and environment of the Lower Shannon and consequently, the environmental sustainability of the Shannon hydroelectric scheme,” he said.

“The roadmap will be implemented during the third River Basin Management Plan cycle which runs from 2022 to 2027.”

Parteen Weir - large concrete structure - standing within and above the River Shannon. Doherty is wearing a hi-vis jacket with ESB written on it. Lacchia is wearing a hat and red coat while looking towards the river. Signs in the foreground state - ESB Fisheries Conservation. Reporter Anthea Lacchia speaking to Dr Dennis Doherty, fisheries biologist with ESB, on a site visit to Parteen Weir.
Source: Alice Chambers/Noteworthy

The EU Biodiversity Strategy aims to make at least 25,000 km of rivers free-flowing again by 2030, by “removing primarily obsolete barriers and restoring floodplains and wetlands”.

A new programme is being developed as part of River Basin Management Plan in Ireland, Noonan told Noteworthy, that will allow for “enhanced regulatory framework for the protection of waters” from pressures relating to the physical shape, barriers and flow patterns of rivers.

This will include “mitigating the impact of existing barriers and the removal of obsolete barriers where necessary and appropriate”, he added.

“Approximately 2,000-7,000 structures” are set to be removed or modified “as a starting point”, according to an update on the roadmap prepared in October 2022 by the DHLGH and released via AIE.

The report that the Department recently commissioned made a series of recommendations for the Shannon Connectivity Project, including new “state-of-the-art” fish passes at Parteen and Ardnacrusha, a barrier to prevent fish from going towards the station, and increasing flow in the original River Shannon to attract fish there.

To facilitate downstream passage, “you could just switch off turbines at night during periods of peak migration of eels”, said O’Connor of Ecofact. This would “make a disproportionate difference”, according to Sustainable Eel Group’s Kerr.

We asked the ESB if they are considering implementing solutions such as this. Moran said that they are “looking at all options to see what can make a difference”. He added: “We are committed to doing better.”

But community groups and locals remain concerned and frustrated over lack of progress to date. Speaking of the Shannon Connectivity Project, locals feel left out of the conversation.

‘We haven’t heard anything,” said Pat O’Connor of the Castleconnell River Association.

“An opportunity exists to make this a ‘Jewel in the Crown’ project, that will enable Ireland to meet WFD [Water Framework Directive] requirements, and show Ardnacrusha/ESB as ecologically friendly generators of ‘green’ electricity.”

Shall Not Pass

Part two delves into concerns over ‘unsustainable’ levels of water abstraction

Have a listen to The Explainer x Noteworthy podcast on our findings

Design for SHALL NOT PASS project featuring a large dam.

By Anthea Lacchia for Noteworthy

Editor: Maria Delaney  Banner graphics: Lorcan O’Reilly  Video production: Alice Chambers

This investigation was proposed and funded by readers of Noteworthy, the crowdfunded investigative journalism platform from The Journal. We also have a number of other projects related to nature and the environment.

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