On May 5th last year, Jane Gilleran took 14 dead fish from a fridge in Inland Fisheries Ireland’s base in Corofin, Co Clare. The previous day, an IFI colleague had found the fish on the lower Ballymacraven river, outside Ennistymon, and stored them safely. The specimens included some of Ireland’s most critically endangered species: European eel, Atlantic salmon and brown trout.
Gilleran, an IFI fisheries officer, used a Nikon microscope to examine their gills, the organ they use to breathe underwater. Healthy gills are bright red, with loosely held comb-like filaments. But that wasn’t what she found: the gills were clogged with gloopy clumps of rust-coloured residue. Some were covered in mucous; others were swollen.
Samples of gill tissue were sent away to a lab for analysis. The results were clear: the thick ketchup-like material was from a chemical sludge containing ferric sulphate, a coagulant used in water treatment plants to remove impurities.
The story of how the ferric sulphate suffocated the fish may never have surfaced were it not for a member of the public who had been walking along the river three days previously. They spotted a rusty brown liquid in the water and realised it was not typical; they took a photograph and sent it to the IFI.
The following day, Gilleran and two other IFI officers arrived at the Ennistymon Water Treatment Plant and found an orange residue around the outfall pipe into the river. The banks were covered in brown sediment. An overhanging tree stump looked like it had been sprayed, Jackson Pollack-style, with a rust-coloured gloop.
The trio entered the treatment plant and took samples from the settlement tanks. They contained highly acidic residue with very high iron levels, consistent with ferric sulphate. Within a day, dead fish appeared on the banks; their mouths were open, indicating they were gasping for oxygen before they collapsed. Some would have died instantly from acidification; others took longer to suffocate.
According to world fish pain expert Dr Lynne Sneddon, a biologist at the University of Gothenburg, the ferric sulphate would excite the fish’s pain receptors (called nociceptors) and inflame the gills, which is painful. “If this happened to animals on land, this would be totally unacceptable,” she said. “The death of such a large number of animals would provoke public outrage.”
[ Seeing fish trying to jump a weir isn’t impressive – it’s tragicOpens in new window ]
An estimated 2,000 fish died, but a lot more may have been killed (for example, young fish, just 3cm long, may have died and floated downstream out of view). Some of the dead eels discovered on the banks were large females, 10 to 15 years old, who may have been on their way to breed in the Sargasso Sea when they died.
The Enistymon plant’s drinking water source is a 250-acre lake in the Burren called Lickeen, a few kilometres away. Ireland depends heavily on surface waters, such as rivers and lakes, for drinking water. (In many EU countries, it is sourced from groundwater.)
The challenge with abstracting water from lakes and rivers is purification; the bits of soil, sand, clay and organic matter must be removed before the water is chlorinated and sent out as drinking water. Ferric sulphate solves this problem by binding to the material and producing clean water. What’s left behind is a sludge. Until 30 years ago, this sludge would have been released into our waterways. Today, it is considered a waste product and must be treated safely under licence.
In 2014, when Irish Water was established and inherited the treatment plants from local authorities, the Ennistymon plant did not have a licence to discharge waste into the river. The Environmental Protection Agency audited the plant that year and several problems were identified, not least that it was operating at 55 per cent above its capacity.
The EPA next audited the plant a week after last May’s pollution incident. It found a litany of issues, including mechanical failures, poor management and a lack of alarms that would have alerted plant operators to a malfunctioning of the sludge treatment process. The sludge was not being stored and removed off-site adequately, and Clare County Council told the EPA that “there is potential for the discharge of sludge to the Ballymacraven river during periods when the wastewater tank is full”.
This potential was realised again just two weeks after the first fish kill, on May 18th, when another member of the public alerted authorities to an orange discolouration in the river. According to the IFI, another sludge release had occurred, with iron levels high enough to threaten fish and aquatic life. No dead fish were found this time; the live fish in the river had been wiped out a fortnight before.
Last month, the Ballymacraven case – described by the solicitor for Inland Fisheries Ireland as an “ecological tragedy” – reached Ennis District Court. Uisce Éireann, which operates on an annual budget of €1.3 billion, pleaded guilty and incurred a fine of €10,000 (the equivalent of €5 per dead fish). According to Uisce Éireann, a €7.5m upgrade to the plant will be completed this year, and the sludge is now removed daily. The catastrophe has galvanised locals to set up a group, Restore Ballymacraven River. It’s unclear how long it will take for the river’s life to recover, or whether that is even possible.
[ Dublin is running out of water. Can the Shannon help?Opens in new window ]
What happened on the Ballymacraven is the result of historic underinvestment in water treatment plants and an assumption that our rivers and lakes are fair game to absorb the pressure, whatever the damage. Some water plants are now under crippling pressure from our ever-expanding population. This growth was a central part of the government’s 2018 strategy, Project Ireland 2040, which planned for an extra one million people in 20 years, along with a promise that this development would be sustainable.
Our looming water crisis, which is also an ecological one, proves it is anything but.
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