Leave only Paw Prints

An important goal of the Acclimatize 2017 – 2023 project was to determine how much each of the pollution sources contribute to faecal pollution in Dublin Bay.  As part of this, the team undertook studies to determine the impact of dog fouling on bathing water quality.

In Ireland, bathing water is monitored by the local authorities during the bathing season, from 1st June to 15th September. The water quality is classified based on the levels of faecal indicator bacteria found in a water sample according to the Bathing Water Directive[1]. These bacteria are called E.coli and intestinal enterococci and are found in the gut of warm-blooded animals, including humans. They are introduced into the water environment through faecal matter. Faecal pollution on beaches can come from a number of sources, such as sewage and animal fouling, including dogs. Dog faeces contains many dangerous pathogens that can pose a significant threat to public health when it is not recovered by pet owners. This threat is particularly evident on public beaches where people are more likely to come into direct contact with dog faeces through swimming and other recreational activities.

The Acclimatize team set out to estimate the impact of dog fouling on bathing water quality on four beaches in Dublin: Sandymount Strand and Merrion Strand in Dublin, and Donabate and Portrane beaches in north County Dublin. The team carried out dog fouling surveys on each beach to estimate the average amount of dog faeces being left behind in one day. GPS was used to mark where each dog poo was found to identify dog fouling hot spots.

Using molecular tools to analyse the source of faecal contamination called microbial source tracking (MST), the Acclimatize team was able to identify the source of faecal pollution from water samples. The team detected the dog MST marker in a number of bathing water samples from around Dublin [2].

The study also involved estimating the levels of E. coli and intestinal enterococci in the faeces of Irish dogs by collecting faecal samples from dog shelters around Leinster. The team calculated that there are almost 3 billion CFU for E. coli and 350 million CFU for intestinal enterococci in one dog poo. This suggests that one dog poo has the potential to fail an area of water (0.5m deep) approximately the size of a tennis court.

  1. EU, Directive 2006/7/EC of the European Parliament and of the Council of 15 February 2006 concerning the management of bathing water quality and repealing Directive 76/160/EEC. Official Journal of the European Union, 2006. 64: p. 14.
  2. Reynolds, L.J., et al., Correlation between antimicrobial resistance and faecal contamination in small urban streams and bathing waters. Sci Total Environ, 2020. 739: p. 140242.

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