As the need for more temporal and spatial monitoring grows due to the pressures from legislation and regulatory bodies, there is an increasing demand for low-cost nutrient sensors for water quality monitoring. The development of novel sensors emerging from new technologies is critical to protect and conserve our planets most valuable resource – water. The power of these new sensing devices can add value and supplement traditional methods of water sampling, collection, storage, and lab analysis, enabling more frequent and real-time monitoring with an increase data collection. Mitigating increased costs, excess personnel, and intensive labour. These devices have the potential to be integrated into a tiered monitoring framework to satisfy the demand to obtain more information about a catchment and its monitoring needs. The future of monitoring will involve satellite, in-situ and air borne devices with data analytics playing a key role in providing decision support tools. The aim of this thesis was to design and fabricated a fully integrated lab on a disc low-cost sensor for rapid on-site detection of phosphate. The sensor consisted of a microfluidic disc for reagent integration and method automation, a motor, an absorbance-based detection system and electronics board. The system is fully portable enclosed in a robust case, to achieve the main objective of translating this device from lab to field. The novel system was validated during three case studies measuring concentrations of phosphate in surface water samples from various catchments across Ireland. A selection of high and low phosphate level catchments was chosen.