Llyn Idwal is an important site for nature and is protected internationally under the RAMSAR convention. Llyn Idwal’s waters are nutrient poor, known as oligotrophic, which allows a sensitive ecosystem, specially adapted to these conditions to thrive. The lake contains almost all the plant species that you’d typically find in an upland oligotrophic lake – such as pillwort (Pilularia globulifera) and awlwort (Subularia aquatica) and water lobelia (Lobelia dortmanna).
To help protect Llyn Idwal’s ecosystem we do not permit swimming. Recent reports of invasive plant species found in nearby lakes (Nuttall’s Waterweed Elodea nuttallii and Curly Waterweed Lagarosiphon major) can have a significant detrimental effect on a lake’s ecosystem. Such plant species can be introduced to a body of water from fragments of plant stuck to clothing, towels, dog hair etc. – to not allow swimming reduces the risk of these species being introduced to Llyn Idwal.
If you’d like to know more, or find lakes where swimming is permitted, please feel free to ask the warden on site.
Thank you for helping us protect Llyn Idwal.