Farming practices and climate change affecting Irish river water quality

Nearly half of rivers carry high levels of nitrates, but finding solutions may not be easy

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In a small pool of water in Dungarvan’s Brickey estuary, three minuscule crabs scuttle across the sand. Encased by strands of seagrass – a protected habitat that attracts seahorses and Brent geese – the puddle is a rare unscathed patch where biodiversity can flourish in this Waterford inlet.

All around is carpeted with a thick lime green sludge. Robert Wilkes, a marine biologist with the Environmental Protection Agency (EPA), says this rotting slime is a perfectly normal part of seaweed fauna. However, when fed a glut of nutrients, such as phosphorus and nitrogen, it will “grow and grow and grow”, suffocating the ground beneath.

“Fields should be green, but your beaches shouldn’t be,” says Mr Wilkes.

Clawing back some gunk, he reveals a tar-coloured sand. This anoxic layer should begin a few centimetres below the surface, allowing a breathing space above for a range of creatures to inhabit. “Those bugs are food for the more charismatic megafauna. All of the things people like, such as seals, fish, birds, otters rely on them. This is all part of the ecosystem and the food web,” he says.

The trouble in this estuary has been created further inland in the lands drained by the Colligan and Mahon rivers and all streams entering tidal water between Cheekpoint and East Point in Co Waterford.

In all, the catchment area covers 665km², including the run-off from Tramore, Dungarvan and Dunmore East. “Every parcel of land up there has the ability to affect what is going on down here at the estuary . . . While the top of this river might be high quality with a perfectly healthy ecosystem, as you go down that river there are more and more inputs coming in,” says Mr Wilkes.

A recent EPA report revealed that almost half of Ireland’s rivers have unsatisfactory water quality levels due to high nitrate concentrations. Excessive nutrient volumes were also found in a fifth of estuarine and coastal water bodies leading to algal blooms.

Increase in nitrates

Despite all of the talk about cutting the amount of nitrates spread on Irish farms, the volume of nitrates reaching coastal waters has increased by 26 per cent since 2012-2014.

Nitrogen in Ireland’s waterways comes primarily from chemical and organic fertilisers used in agriculture. EPA scientists are particularly concerned about river catchments in the south and southeast of the country where intensive farming and freely draining soils lead to higher losses of nitrogen. While waste-water discharge is the primary polluter in Dublin’s Liffey-Tolka catchment, agriculture is responsible for up to 85 per cent of nitrogen in some rivers in predominantly rural catchments in the south and southeast, according to recent EPA analysis.

However, it would be wrong to assume that simply reducing farming activity would be the most effective way of solving the problem, says catchment scientist Per-Erik Mellander from Teagasc’s agricultural catchments programme.* “Agriculture is a source, and without the source there would be no loss. But then there is the complexity of the landscape and the changing climate,” he explains.

His research team has found that the physical and chemical make-up of a soil has an “overriding” influence on the volume of nutrients lost to water sources. Heavier and poorly draining soils cause water run-off and phosphorus pollution, while softer soils facilitate nitrogen leaching down into groundwaters.

With drier summers and wetter winters, climate change is also increasingly to blame, he says. Mr Mellander points to the extreme drought of 2018 when high nitrate concentrations were observed in all six catchments monitored by the programme.

Launched in 2018, Teagasc’s agricultural sustainability support and advice programme (ASSAP) liaises with farmers in 190 districts across the State that are regarded as the most important for water quality.

Programme co-ordinator Noel Meehan says the new approach is “much more targeted” and collaborative than the previous “one-size-fits-all” enforcement model which coincided with a decline in water quality in Ireland.

Advisers work in tandem with local authority-appointed scientists to find the local sources of nitrate pollution, and to do something about the problem once it is located.

“It is now much more catchment specific. You need the right measures in the right place . . . We go and talk to the farmers in the fields to identify areas of the farm that need to be addressed,” says Mr Meehan.

There are simple one-off fixes, such as redirecting a farmyard pipe away from a water source. But Meehan says nearly 75 per cent of the water pollution is caused by diffuse losses, which are “much more difficult” to correct.

Some long-standing habits among farmers cause problems, such as the “silly” one of spreading slurry from piggeries when rain is forecast, Mr Meehan tells The Irish Times.

Habits improving

Nearly three years on, there are signs that habits are improving in the districts focused up by the ASSAP, says Mr Meehan: “It is early days yet. The proof of the pudding will be in the results to come,” he adds.

Kilkenny dairy farmer Cathal Moran has known how farmers can damage, or help water quality for “donkey’s years”, but he notes that there has been a ramping up of awareness and engagement over the last three years.

Local environmental meetings are “non-stop at this stage”, he says, adding that farmers “understand these things a lot better than even two or three years ago”.

Low-emission slurry spreading has been obligatory on intensively stocked farms since January, but Mr Moran was “ahead of the curve” when he got a grant to change equipment several years ago.

The grant made the change a “no-brainer” decision, he says, adding that constant engagement with farmers and incentives to get them to change habits are key.

“There are still some people saying that they should be able to spread slurry in the winter. They just don’t actually understand the science behind the regulations . . . If you give farmers the right incentives they will push and improve,” he says.

How long would it take to reverse the damage done to Ireland’s water? It is complex, says Mr Mellander. Some areas can recover within a year. Others could take two decades to flush out excess nutrients. “Even if you stopped farming today you would not see a direct response. There would continue to be nutrient loss,” he says.

The Department of Housing, Local Government and Heritage is currently devising the next river Basin management plan, which the EPA says must deliver “real and sustained” water quality improvements. It is “widely accepted”, the agency says in its submission to the department, that the first management plan spanning 2009-2015 did not generate projected improvements, while the second (2018-2021) “will also not deliver the scale of improvements required”.

Mr Wilkes holds on to optimism that Government, farmers and local communities are beginning to see water quality as a “shared responsibility”. It is crucial that recent efforts do not ebb.

“There are no quick fixes or simple answers . . . We have to have a bit of patience because the ecosystem will respond slowly.”

* This article was amended on September 18th, 2021