Water Quality Monitoring Around Llyn Cwellyn

As part of Project Torgoch, we have been conducting weekly water quality testing of the inlets of Llyn Cwellyn. The aim of this testing is to build a baseline dataset and identify where pollutants may be entering the lake in addition to sondes which are being installed in December.

Each week, we have been testing multiple inlet sites and recording temperature, ORP, pH, dissolved oxygen, conductivity, TDS, and nitrates. These measurements provide insight into what each stream is bringing into the lake and highlight any areas that may be contributing to declining water quality.

The results

As it is early days no conclusions can be drawn yet, but these early results show clear differences between inlets.

-Some streams show very high nitrate levels, with readings exceeding 600–1300 mg/L at certain sites.
-Others remain consistently low, suggesting cleaner upstream conditions.
-There is also conductivity and TDS spikes in specific areas, indicating possible nutrient or sediment inputs.
-pH remains mostly neutral, and dissolved oxygen is high across all sites, typical of cold upland runoff.

The hotspots in nitrate, TDS, and conductivity suggest potential pollution sources likely linked to land use pressures. This weekly dataset will allow us to track patterns, identify repeat problem areas, and inform management actions.