Old River Shannon Foundation

29/04/2026

Termonbarry Weir on the upper River Shannon last week. The video shows a so-called “temporary” fish pass that was installed here approximately 25 years ago.

This weir is located upstream of Lough Ree and blocks fish passage to a substantial portion of the upper Shannon catchment, including the Boyle and Lough Allen systems.

This “temporary” fish pass does not work, and fish migration remains obstructed at this site. This structure was installed following a failed proposal for a hydroelectric development and was never designed as a properly engineered fish pass. It is loosely based on a pool pass but does not meet the requirements of a standard design.

In practice, it provides limited attraction flow, and fish are unlikely to locate the entrance. Flow through the pass is low, the gradient is too steep, and the structure includes excessive jumps. Angular edges present an additional risk of injury. Leakage beneath the structure further disrupts flow patterns, drawing fish away from the entrance into dead-end areas.

Pool pass designs are also inherently unsuitable for species such as eels and lampreys, meaning that even if the structure functioned as intended, it would not provide passage for key migratory species. There is no evidence that the pass is used by any fish species, and no monitoring has been undertaken. The weir and fish pass are owned and managed by Waterways Ireland.

Historically, large runs of salmon passed through Termonbarry on their way to spawning areas in the upper catchment, and this section of the river also supported important eel fisheries. While the most significant barriers on the Shannon are the hydroelectric dams in the lower river, structures such as Termonbarry Weir have also contributed to the long-term loss of migratory fish from the system.

None of the dams and weirs along the River Shannon provides adequate fish passage.

26/04/2026

Rooskey Weir on the upper River Shannon earlier this week. This weir is located upstream of Termonbarry Weir, between Lough Forbes and Lough Bofin.

This is just one of several navigation weirs along the main river that are causing fish passage problems. None of the dams and weirs along the River Shannon have adequate fish passes.

24/04/2026

Termonbarry weir on the upper River Shannon this week. A "temporary" fish pass was installed here 25 years ago. This fish pass does not work and fish migration remains blocked at this site. None of the dams and weirs along the River Shannon have adequate fish passes.

25/03/2026

A major new report under the UN Convention on the Conservation of Migratory Species has highlighted what is being described as a largely overlooked biodiversity crisis: the collapse of migratory freshwater fish populations. The findings are stark. Global populations have declined by around 81% since 1970, making them one of the most rapidly declining vertebrate groups on the planet.

These species, including salmon, eels, lampreys, and shad depend on free-flowing rivers to complete their life cycles. The report identifies habitat fragmentation from dams and barriers, altered flow regimes, pollution, overfishing and climate change as the primary drivers of decline. It also highlights a major policy gap, with hundreds of migratory species requiring coordinated international protection but only a small proportion currently listed under global agreements.

While global in scope, the relevance to Ireland is immediate and clear. Many of the species highlighted, including Atlantic salmon (Salmo salar) and River lamprey (Lampetra fluviatilis), are key qualifying interests of Irish SACs and are now listed by the IUCN as ‘Near Threatened’. The pressures identified in the report closely mirror those affecting Irish rivers: barriers to migration, hydrological alteration, declining water quality and cumulative catchment pressures.

Perhaps the most important message is the emphasis on connectivity. Migratory fish require entire river systems, from headwaters to estuaries, to function as ecological corridors. Managing rivers as fragmented units, or relying on localised mitigation, is fundamentally inconsistent with their ecological requirements.

River restoration requires restoring connectivity, ensuring appropriate environmental flows, and addressing barriers at a catchment scale. Without this, the long-term decline of these species is likely to continue, despite formal protections.

Read the summary report with links to the main report here:https://assets.worldwildlife.org/www-prd/documents/FINAL_26_3202_UN_CMS_Migratory_Fish_Report_v6c_031826_uL4zPT8.pdf

22/03/2026

03/03/2026

Arterial drainage maintenance works on the River Morningstar at Athlacca, Co. Limerick. These works were completed by the Office of Public Works (OPW) during the period November 2025 to January 2026. I visited the site last week when the machines had already left the site. However, I have been provided with photos showing the works underway.

Significant areas of riparian woodland have been removed, and alluvial woodland was also cleared from islands within the river. There is evidence of substantial silt mobilisation and in-stream disturbance. The riverbanks have been destabilised as a result of the removal of trees and other vegetation. Although silt fences are now present, they did not prevent fine sediment and wet soil from entering the channel during the work. Machines tracked instream during the salmonid close season.

This damage will affect the river for years to come, and a permanent loss of riparian woodland has occurred. The removal of woodland set back from the riverbank extends well beyond what would be considered to be river maintenance works.
The River Morningstar is an important salmonid nursery and spawning tributary of the River Maigue. The lower reaches of the River Maigue form part of the Lower River Shannon Special Area of Conservation (SAC) and the River Shannon and River Fergus Estuaries Special Protection Area (SPA).

Works like these are completed under the Arterial Drainage Act (1945). They are supposed to protect against flooding, but in reality, they have the opposite effect. By draining water off farmland too quickly, river works like this increase flood risk in downstream urban areas. This work was completed to protect wet farmland in a natural floodplain.

We do need flood mitigation measures - but they need to be effective, sustainable, and based on evidence. In most cases that means slowing the flow of water through natural flood management techniques and restoring floodplains and wetlands to absorb excess water rather than pushing it downstream.

We need to reform the Arterial Drainage Act (1945) and recognise the vital role that floodplains, alluvial woodlands and wetlands play in flood management and mitigation. Instead of fighting against nature, we should be working with it to ensure communities are truly protected in the long term. A healthy, functioning river catchment benefits everyone - not just wildlife, but the people who live alongside it too.

PS: The Maigue Rivers Trust have been such a dissapointment. They may not have any control here, but I don't see them speaking out about this either. We are 10 years in with this trust now and nothing has improved in the catchment. We need action - not summer fetes! Meanwhile Inland Fisheries Ireland have faded into irrelevance.

27/02/2026

Arterial drainage maintenance works on the River Morningstar at Athlacca, Co. Limerick, this week. The works had already been completed when I visited the site; however, their impacts are likely to affect the river for months to come.

I understand that these works were undertaken by the Office of Public Works (OPW) under the Arterial Drainage Act (1945).

Significant areas of riparian woodland have been removed, and woodland was also cleared from islands within the river. There is evidence of substantial silt mobilisation and in-stream disturbance, including machines tracking instream during the salmonid close season. The riverbanks have been destabilised following the removal of vegetation. The silt fences used were limited in extent and non-standard in design and did not prevent fine sediment and wet silt from entering the channel from the cleared riparian areas.

The scale and extent of the works appear more consistent with a flood relief scheme than routine arterial drainage maintenance. However, there is no publicly available evidence of planning permission having been obtained. The removal of woodland set back from the riverbank extends beyond what would be considered to be maintenance works. New access gates have also been installed for adjoining landowners. The clearance of riparian woodland follows similar works I previously highlighted on the nearby River Maigue at Bruree.

The River Morningstar is an important salmonid nursery and spawning tributary of the River Maigue. The lower reaches of the River Maigue form part of the Lower River Shannon Special Area of Conservation (SAC) and the River Shannon and River Fergus Estuaries Special Protection Area (SPA).

When the Maigue Rivers Trust was established a decade ago, there were hopes that management of this long-suffering catchment would improve. However, water quality has continued to decline. During the most recent EPA monitoring cycle, completed in 2023, unsatisfactory ecological conditions were recorded at all monitored stations on the River Maigue. Siltation and nutrient enrichment were recorded at every station on the River Morningstar during this survey. The principal pressures on water quality in the catchment are agricultural activities and urban wastewater discharges. However, hydromorphological pressures are also significant, and arterial drainage works have been identified by the EPA as a major source of sediment input in the catchment.

Fish stocks have also continued to decline and are affected by water quality deterioration, arterial drainage works, and numerous migration barriers. There are 12 ornamental concrete weirs, similar to Annacotty Weir, in the lower reaches of the River Maigue alone. White-clawed Crayfish have disappeared from the catchment due to crayfish plague.

If we are serious about restoring rivers in Co. Limerick, we will have to address the cumulative pressures affecting catchments like the River Maigue. Improving water quality requires meaningful reductions in nutrient and sediment inputs, the protection and restoration of riparian areas, and a shift towards river management approaches that prioritise natural flood management measures. Most importantly, we need to urgently reform the Arterial Drainage Act.

26/02/2026

Schon wieder Aal-Gemetzel am Hochrhein!

Wandernde Aale werden in den Turbinen der Rheinkraftwerke zerfetzt. Für über 90 Prozent endet jede Passage tödlich. Und das bei einer Art, die in der Schweiz als vom Aussterben bedroht gilt und national geschützt ist.

Seit 2011 ist die ökologische Sanierung gesetzlich vorgeschrieben. Passiert ist am Hochrhein bis heute praktisch nichts.

Wir fordern endlich konkrete Sofortmassnahmen. Schutz darf kein Lippenbekenntnis bleiben.

26/02/2026

The fatal flaw in the Proposed Water Supply Project for the Eastern and Midlands Region.

This video shows Parteen Regulating Weir on the Lower River Shannon last week. The intake for the proposed water supply scheme is located just upstream from here. This weir was built in the 1920s as part of the Shannon Hydroelectric Scheme. It regulates water levels on Lough Derg and diverts most of the river’s flow to Ardnacrusha Power Station. For over 90% of the time, only the statutory minimum “compensation flow” of 10 m³/sec (cumecs) is left in the more than 15 km of river downstream of the weir - the stretch known as the “Old” River Shannon.

This reach forms part of the Lower River Shannon Special Area of Conservation (SAC), designated under the EU Habitats Directive for species including Atlantic salmon. However, migratory fish stocks in the Shannon have collapsed, and the key pressure is the long-standing water management regime and fish passage constraints at the ESB dams.

Lough Derg is a European Site designated as a Special Protection Area (SPA) for bird species including Common Tern. Terns nest on low-lying islands that are highly sensitive to water level fluctuations caused by the operation of the Parteen Regulation Weir. No remaining terns were recorded on the lake during the last survey completed in 2024.

When I recorded this video a flow of 130 cumecs was being left in the river downstream of Parteen Regulating Weir. This only happens during flood conditions when the capacity of Ardnacrusha Hydroelectric Station is exceeded. When these releases happen the natural character of the river immediately returns, and the famous “Falls of Doonass” roar again.

The Lower River Shannon can be restored with a management decision, and it is not a Heavily Modified Waterbody (HMWD). Similarly, Lough Derg can be restored to a more natural lake with more sensitive water management. Most of the ecological impacts of the Shannon hydroelectric scheme are the result of unsustainable water management – not the physical presence of the dams. The fish follow the water and no fish pass could ever work if you are diverting up to 97% of the flow in the river.

Here is where the fatal flaw in the proposed Water Supply Project lies. The new abstraction is embedded within, and dependent upon, this same regulated system. The planning application acknowledges that water management will need to change in the future - but it does not define what that change will look like, nor assess the abstraction against the environmentally compliant regime that will be required.

The proposed abstraction is not trivial. It represents roughly 35% of the flow currently left in the Old River Shannon for an average of 93% of the year. During droughts, lake levels will have to be regulated even more to maintain both the compensation flow and the new abstraction. The implications for restoring the Lower River Shannon SAC - and for Common Terns on Lough Derg - have not been properly assessed.

For decades, the ecological consequences of the Shannon hydroelectric scheme have been deferred. Instead of first restoring the river to meet EU environmental obligations, we now have a proposal for a major new abstraction layered onto an already highly constrained and unsustainable system.

Read my report which supports the submission from Friends of the Irish Environment at this link https://tinyurl.com/mu654dah

07/01/2026

Male Atlantic salmon (Salmo salar) on the Lower River Shannon at Castleconnell, Co. Limerick.

This salmon has completed spawning and is in very poor physical condition. When Atlantic salmon enter freshwater, they stop feeding and expend almost all remaining energy on migration, competition, and reproduction.

Although Atlantic salmon are not fully semelparous (unlike Pacific salmon, Oncorhynchus spp.), the vast majority of fish spawn once and then die. Mortality is often highest in males that engage in prolonged fighting and nest defence.

Survivors, known as kelts, are typically in severely depleted condition and face further high mortality during downstream migration. Historical scale-reading studies on Atlantic salmon in the River Shannon show that repeat spawners typically comprised only about 1–6 % of the spawning population.

This level of post-spawning mortality is a natural part of the Atlantic salmon life cycle, but it is greatly exacerbated by barriers, reduced flows, water-quality declines, and other human pressures that limit recovery and successful return to sea.

Iteroparity (repeat spawning) can provide a buffer against unpredictable events that jeopardise population recruitment and may be a valuable source of genetic variability. Females are often more abundant as repeat spawners than males and may contribute disproportionately to recruitment due to their high fecundity, which is linked to body size.

Atlantic salmon is a Qualifying Interest of the Lower River Shannon Special Area of Conservation (SAC). The species is at unfavourable conservation status in the river due to factors including migration barriers, water abstraction and flow regulation, habitat loss, and declines in water quality.

06/01/2026

Otter versus Salmon. An Otter (Lutra lutra) battles it out with an Atlantic salmon (Salmo salar) on the bank of the River Mulkear, Co. Limerick.

The determination of the salmon to get back into the river, despite the odds, highlights the resilience of this species. Salmon only need half a chance, and we are not giving them that.

The River Mulkear forms part of the Lower River Shannon SAC. Both Otter and Atlantic salmon are Qualifying Interests of this Natura 2000 site.

Native natural predators are not a key factor in the decline of salmon populations; predation is a natural and ecologically important process that salmon have evolved with.