The Ecosystem Approach to environmental management, with its explicit acknowledgment of the environmental, social and economic elements within ecological systems, is becoming increasingly adopted by managers and policy makers. However, there are few specific prescriptions as to exactly how these different elements should be integrated, or examples where historical changes have been tracked. Here, we assess the potential benefits and challenges of applying an Ecosystem Approach to management using one particular method, the Holistic Ecosystem Health Indicator (HEHI), which integrates data from the ecological, social and interactive dimensions into a single composite index of ecosystem 'health'. We apply it to one of the best-documented catchments in the UK, the Ythan Estuary in Aberdeenshire, Scotland, based on a 50-year time series of data. The evaluation of ecosystem health over time is lacking in previous applications of HEHI, yet is crucial for the assessment of the utility of this approach to ecosystem management. The application of HEHI yielded different insights to those revealed from the traditional application of biophysical approaches for managing the Ythan. Overall, ecological health declined through the 50-year period, although it increased marginally in the last decade, while social and interactive dimensions followed the opposite trend. HEHI indicated a steady increase in ecosystem health overall except for the last decade, when it declined marginally. Our evaluation of the application of ecosystem health for the Ythan revealed major data gaps. For the approach to be used more widely, issues of data availability and the temporal and geographical mismatch between ecological and social research boundaries need to be overcome.