Sondes monitoring at Llyn Cwellyn

As part of Prosiect Torgoch we are starting a program of intensive water quality monitoring in the upstream catchment of Llyn Cwellyn to further understand nutrient inputs to the lake.

Llyn Cwellyn is an oligotrophic lake, meaning it is low in nutrients and currently offers the best habitat for Arctic charr in Wales. However, in recent years nutrients levels have gradually increased causing a drop in deep water dissolved oxygen. These cool deep water zones provide important refuge habitat for Arctic charr during the warm summer months, but the species is highly sensitive to low dissolved oxygen, meaning the conditions are becoming increasingly challenging for Arctic Charr.

The survey programme will involve continuous monitoring of nutrients levels in the Afon Gwyrfai using sondes. These instruments will remotely measure and log nitrates, ammonium, dissolved oxygen and turbidity at 30-minute intervals. Over the next year, Antony, the NWRT officer for Prosiect Torgoch, will take spot samples from the many small streams that enter the lake.

[image description] example of Sondes monitoring

The data collected from the surveys will help us understand nutrient sources and identify catchment restoration projects to improve and protect water quality and the deep water habitat for Torgoch at Llyn Cwellyn.

Prosiect Torgoch is funded by the National Heritage Lottery Fund.