Acclimatize 2017 – 2023 was a project carried out by researchers in Ireland (University College Dublin (UCD)) and Wales (Aberystwyth University). Our aim was to work out how bathing waters at the seaside become polluted in a way that can impact on public health, and how climate change may affect the quality of these waters in the future. The Acclimatize project was part-funded by the European Regional Development Fund through the Ireland Wales Programme 2014 – 2020. Acclimatize began in February 2017 and finished in June 2023.

Who did we work with?

In Ireland, we worked with Dublin City Council, Dún Laoghaire-Rathdown County Council, Fingal County Council, the Environmental Protection Agency, Uisce Éireann (formerly Irish Water), the Dublin Bay Biosphere Partnership and Waterways Ireland.

In Wales, we worked with Dŵr Cymru Welsh Water, Natural Resources Wales and representatives of Welsh Local Government (Cyngor Sir Ynys Môn/Isle of Anglesey County Council, Llanbadrig Community Council, Cyngor Sir Ceredigion County Council, Cyngor Sir Penfro/Pembrokeshire County Council) the Llywodraeth Cymru/Welsh Government and relevant non-governmental organisations (through the Water and Health Partnership for Wales (Bathing Waters Group)).

What we did

We used a combination of extensive fieldwork including beach transects, marine sampling and dog fouling surveys, laboratory analysis and hydrometric and meteorological monitoring to gather information about our study sites. Through microbial source tracking we were able to determine the source of pollution (i.e. humans, dogs, gulls, cows). We then combined this information with existing knowledge about river courses, weather and climate predictions to build statistical predictive and hydrodynamic models.

In the short term, these models can be used to figure out the risk to the bathing waters. We also built longer-term predictions up to the end of the century that take climate change into account. This information will help policy-makers and local authorities to protect the valuable amenities and resources provided by bathing waters.


  • Sandymount Strand, Dublin
  • Merrion Strand, Dublin
  • Dollymount Strand, Dublin
  • Donabate (Balcarrick Beach), Dublin
  • Portrane (Brook Beach), Dublin
  • Grand Canal Basin, Dublin


  • Cemaes Bay, Anglesey
  • Traeth y Dolau/New quay North, Ceredigion
  • Traeth Gwyn, Ceredigion
  • Nolton Haven, Pembrokeshire

Summary of findings

Pollution pressures

  • Nearshore water quality is generally poorer than offshore water quality.
  • Faecal indicator measurements can vary by 100 – 10,000 fold in one day.
  • Causes of poor water quality:
    • Polluted streams discharging onto the beaches (human and agricultural pollution).
    • Dog fouling – a single dog poo is enough to contaminate an area the size of a tennis court.
    • Birds – when birds congregate, e.g. during migration, they can cause localised pollution.

Climate change

  • Patterns of rainfall are expected to change and may lead to drier summers and wetter winters. Climate change impacts on bathing water quality will therefore vary with season.
  • Water quality may improve due to:
    • Rising sea levels leading to dilution of pollutants.
    • Drier summers may mean less surface water and discharges from CSOs.
  • External factors may impact water quality in the future, e.g. upgraded wastewater treatment facilities or changes to dairy herd numbers.


  • We now have an excellent understanding of the microbial and hydrodynamic characteristics of the streams, rivers and bathing waters in the Acclimatize study areas.
  • Development of statistical predictive and hydrodynamic models of urban and rural bathing waters giving us a greater understanding of the dynamics of bathing water quality.
  • Development of evidence-based models enabling an understanding of the connectivity between the site of pollution discharge and potentially impacted bathing waters.
  • We now have a greater understanding of the climate change effects on factors contributing to the faecal contamination of bathing water.
  • Outreach activities highlighting the impact of dog fouling on water quality.
  • Support from the Ireland Wales Programme enabled our participation in SARS-CoV-2 wastewater surveillance projects which led to the establishment of National SARS-CoV-2 Wastewater Surveillance Programme in Ireland.


  • Enabling our project partners to make evidence-based, targeted interventions to improve water quality of streams, rivers and bathing waters.
  • Providing scientific background to support policy decisions required to manage bathing waters.
  • Development of models to predict within day water quality. Being able to predict poor water quality means we can reduce health risk by warning people in advance.
  • Increased understanding of the potential impacts of climate change on bathing water quality, enabling our project partners to future proof investments aimed at improving water quality.
  • The outcomes and results of Acclimatize are being used to inform the revision of WHO and EU standards.
  • By improving water quality, we reduce the risk of illness from pathogens derived from faecal contamination.

This project has been part funded by the ERDF though the Ireland Wales Programme 2014 -2020.

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