I went to the HSE site but found nothing about Galway or Ennis,just general (but helpful) info.

How does anybody know that the problem is caused by agriculture or septic tanks? It could be caused by pets, bad human hygiene or pure bad luck.

Milwaukee, Wisonsin USA had a crypto outbreak, and it is a big city. No agriculture.

Beware of people who supply quick answers to complicated problems. They may be right; they may be wrong.