Although the Dart river catchment in South West England is predominantly classified as being of good status it is notable that this is not the case for pH on the West Dart River, which is failing under the Water Framework Directive (WFD). The efforts of previous studies and modelling have found that this is largely due to anthropogenic influences and that even under best case scenarios for natural recovery, this is unlikely to occur. It has therefore been agreed with stakeholders to trial a program of calcium carbonate (CaCO3) addition to the West Dart river in order to raise pH with the expectation of improving both chemical and ecological status. The PhD research project (co funded between Plymouth University and WRT) involves undertaking both chemical and ecological monitoring in conjunction with modelling to fully characterise the current conditions of the area and the impacts that the trial will have on the West Dart. The overall aim is to explore if CaCO3 application can prevent pH troughs from dipping below levels biologically relevant to salmon survival rates (c. <pH 5.5) and assess any changes in diatom, macro-invertebrate and macro-algal biological assemblages of the test site against recognised biotic indices in order to contribute to meeting good ecological status. Background to the project will be presented with monitoring data for chemistry and ecology.