Case Studies
Monitoring Nutrients Using CWS Sensors – Teifi and Ceredigion Coast
The question: Could better rural land management drive significant improvements in water quality?
In March 2024, an extensive nutrient monitoring study in the Teifi catchment was started and the first CWS phosphate and nitrate sensors were installed alongside multiparameter sondes. Since then, the number of sites and deployed sensors has steadily grown. The latest additions are two marine sites in New Quay and Aberystwyth. Ammonia sensors will be added in 2027 to supplement our existing nitrate and phosphate monitoring at both river and marine sites.
To obtain a comprehensive picture of water quality across the catchment, the continuous sensor data are complemented by river discharge data, rainfall data, and nutrient spot sample data from NRW (Natural Recourses Wales), as well as spot sample data from citizen science measurements and ClearWater Sensors staff.
In February 2026, our Head of R&D, Alex Beaton, presented findings from the nutrient monitoring study in the Teifi catchment at the Ceredigion Marine Monitoring Conference.
Two of the study’s key findings were:
1. Phosphate concentrations frequently exceeded SAC (Special Area of Conservation) compliance targets, with large peaks in phosphate occurring after storm events.
2. The highest phosphate loads were measured in two tributaries of the Teifi with no significant urban land use or sewage inputs.
Relying on sporadic spot samples only, the magnitude and timing of phosphate pollution issues (especially in the tributaries of the Teifi) would not have been detected. Spot samples are valuable and important for confirming the correctness of the CWS sensor results. But phosphate concentrations are changing rapidly and sending staff to take samples every 30 minutes or every hour is not feasible.
Automated continuous monitoring is therefore of utmost importance.
The study also highlights how important management and regulation of agricultural practices in rural areas is for improving water quality. Real-time data from Clearwater Sensors are being exported to the West Wales Nutrient Management Portal, helping them to take a responsive approach to catchment management.
Identifying phosphate sources in the Hampshire Avon
Read about how a lab-on-chip phosphate sensor was deployed in the river Avon in the United Kingdom to help determine phosphate sources in the catchment. The sensor operated remotely for a 9‑week period, sampling every 30 minutes and communicating data in real time over the mobile phone network. Download the case study here.
