Dog Owners Don’t Understand the Damage a Single Poo Can Do to a Bathing Beach, Researcher Says

Patricia Cooney bends down at the Sean Moore entrance to Sandymount Strand, her hand wrapped in a small plastic bag.

Behind her, Millie waits patiently as Cooney scoops up the collie’s poo, occasionally prancing up to check out the other dogs pulling walkers onto the strand.

Not enough people pick up their dogs’ poo around here, says Cooney, and points down the beach. “There’s a dog poo up there I saw, it’s just disgusting.”

People may think leaving dog poo on a beach is harmless, says Wim Meijer, a professor of microbiology at University College Dublin.

“They probably think, like, okay, well, the water will just come in and wash it away and it will have no consequences,” he says.

Actually, though, research by Meijer and his colleagues at Acclimatize – a project looking at what’s polluting seaside bathing waters in Ireland and Wales – has found a surprising level of pollution from dog poo in Dublin Bay, albeit alongside other pollutants.

A single dog poo can contaminate water in an area the size of a tennis court, if it is as shallow as Merrion Strand and Sandymount Strand, says Meijer, where the water is half-a-metre deep at high tide.

Meijer says more education about the impacts of not picking up dog poo is needed. Cooney, and a local councillor, say there needs to be much tougher enforcement of the law.

How Bad?

During the 2021 bathing season – which ran from 1 June to 15 September – the council’s Protection of Water Bodies Office (PWBO) and researchers at UCD’s School of Biomolecular and Biomedical Science tried new ways to measure whether poo contaminating the water off Sandymount Strand came from humans or animals, said a recent council response to Labour Councillor Dermot Lacey.

The UCD team is working for Acclimatize, the project studying pollution in Dublin Bay in collaboration with the four Dublin local authorities and other government agencies such as Irish Water.

They used PCR tests to track contamination in water samples from different beaches in Dublin Bay, like Merrion Strand, Sandymount Strand, Fingal Bay Beach, Donabate and Portrane.

“We have ways to look at the biological sources of pollution so we can identify waters contaminated by dogs or by gulls or by humans or horses or pigs,” says Meijer.

“Dublin Bay is subject to many different types of contamination coming from rivers and streams,” he says, including the nearby wastewater-treatment plant in Ringsend.

From testing water samples, dog fouling emerged as a significant cause of pollution in Merrion Stand and Sandymount Strand he says, which emerged from testing the water samples for faecal contamination.

To determine the extent of dog fouling, the team went out for nine days over the summer to count poos on beaches and mark their GPS coordinates.

They weighed the poo and calculated the level in water of e-coli and enterococci, the dangerous bacteria, he says.

On Merrion and Sandymount Strand, the team collected an average of 1.1kg of dog poo each day.

One day, they found 30 pieces of poo on these beaches, and on average found 15 pieces.

Other Factors, Too

Elm Park Stream, which is fairly contaminated at times, and at other times, less contaminated, leads into Merrion Strand, Meijer says. Depending on the day, dog fouling may be a greater or lesser extent of the pollution problem on the strand.

“To say like, if you take away all the dogs on the beach, then suddenly the water quality will be excellent, that is not true,” he says.

“It’s not possible to say okay, this is the main 80 percent, but it is certainly significant. But the main source of contamination is the stream,” says Meijer.

The council’s response to a query from Labour Councillor Lacey does list measures it, and other government agencies, have been taking to tackle pollution into the Elm Park Stream.

Among them, it says, Irish Water removed a combined sewer overflow which opened into Elm Park Stream, it says. “This substantial undertaking has delivered the removal of a significant source of pollution during heavy rainfall events.”

Dealing with It

Near the entrance to Sandymount Strand on Monday, Cooney spots a fresh dog poo in the sand, and grimaces.

“Children, all those little kids down there walking past that is absolutely disgusting,” she says, pointing at a pair of kids further out towards the sea, playing near the waterline.

If water quality gets too poor, the beaches are closed, in line with an EU directive. Merrion Strand has been declassified as a bathing area since 2020, because of persistent pollution.

Swimming in water contaminated by e-coli and enterococci puts people at an increased risk of diarrhoea, gastrointestinal problems, or even respiratory disease if the water is ingested, Meijer says.

Or worse even, he says, depending on what organism a swimmer swallows. “It can be much worse. I mean in extreme cases, very unlikely, can be fatal or can cause a fairly nasty upset tummy.”

Lacey, the Labour councillor, says there should be a community warden posted at beaches in Dublin.

“It would be a combination of litter warden, dog warden and traffic warden,” he says, who could spot and fine persistent dog owner culprits.

There also should be a second wastewater-treatment site, he says, as Ringsend wastewater treatment plant is over capacity.

“They’ve been talking about building a waste treatment plant on the northside for at least 25 years now,” he says, which would be in Clonshaugh.

Meijer says that more education is needed for dog walkers. “I think the main problem is, is that the people who walk the dogs on a very large beach, do not seem to understand that it has an impact.”

His team is commissioning an animation to make it clearer just how much one dog poo can impact water quality. “It might actually be sufficient to actually cause beach failure,” he says, which is when beach water is too polluted to swim in.

Cooney says she’d like to see the laws against dog fouling enforced. She’s seen the dog warden out checking for dog licences, she says, but no enforcement on fouling.

“Nobody has ever said, how many bags have you got in your pocket,” she says, “Or have you picked up after her?”