Citizen scientists find high fertiliser levels in our rivers and lakes

Evidence of possible sewage and fertilisers in water

Photo: Robert Jones
Photo: Robert Jones
Stock photo

Caroline O'Doherty

One in five of the country's rivers and lakes had high levels of farm fertilisers, a new citizen science project has found.

The WaterBlitz project, run by Dublin City University (DCU), recruited more than 800 members of the public to collect samples from their local waterways over four days last month.

Volunteers carried out testing themselves with specially supplied kits and uploaded the results via an app for DCU scientists to collate.

Project lead Dr Susan Hegarty, of the DCU Water Institute, said the joint effort was invaluable.

"There is no way that a small team of staff could cover hundreds of collection points and samples in a few days, but bringing the public on board has made that possible, and we're delighted so many got involved," she said.

She was not so delighted with the findings, however. Of the 373 locations inspected along rivers, lakes, streams and canals, more than a third were littered, including well-known beauty spots such as the Upper Lake at Glendalough in Co Wicklow.

Dr Susan Hegarty hailed the water-testing by volunteers
Dr Susan Hegarty hailed the water-testing by volunteers

Almost one in five had high levels of nitrates, which usually indicates that fertilisers have been washed from surrounding lands into the water. Nitrates encourage excessive growth of algae, which can starve the water of oxygen and kill other plant and animal life.

Phosphates, which most often come from detergents and domestic sewage, were also widespread, although there were fewer waterways affected by high levels.

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They can have the same effect as nitrates, causing previously healthy lakes and rivers to become choked with algae.

But if they indicate the presence of human waste, that is a warning sign of a potentially bigger problem - the cryptosporidium parasite.

"We've seen in the last week how fragile our water ecosystem is, with over 600,000 people in Dublin, Meath and Kildare and others around Knock having to boil their water," said Dr Hegarty.

Plastic was the main find among the litter detections. Left in water for long periods of time, it breaks down into microplastics that can end up being unknowingly ingested by animals and people.

Despite the problems detected, Dr Hegarty said there were positive findings.

"What's surprising is the good quality of a lot of our waterways. It shows when there is awareness in a particular area. So, for example, there are groups who have done a lot of work along the Dodder river and that's evident in the results. With a little bit of love, we could improve the quality of all of them."

The vast majority of the volunteers and samples came from the greater Dublin area with the Liffey, Dodder and Tolka rivers and Royal and Grand Canals particularly well covered.

But testing was carried out in the midlands, west and south as well.

Full details of the results from individual waterways will be available in December.

Dr Hegarty said the plan was to expand and repeat the exercise every year to build up a comprehensive database, and to encourage a wider participation from outside the greater Dublin area.

The project was run simultaneously in Paris, London and Luxembourg under the auspices of the Earthwatch charity. Early results show Irish waterways had some of the highest levels of litter and algae.

Irish Independent

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