In this paper a model is put forward for setting targets for ecologically sustainable development in a region. A case study approach facilitates the development of the environmental impact model of Ehrlich and Holdren (1974). Targets for a region's population and water quality are discussed in some detail with the help of the model. The region, the far north of Queensland, Australia, is centred on the Cairns District, which is growing rapidly due to tourism. As well as exploring the environmental impacts of change in the interaction variables of population, consumption and technology, the article contains discussion on setting environmental rehabilitation targets. Major regional externalities would be removed by the achievements of regional water quality improvements. However, other externalities could be generated by the imposition of a limit on regional population. A regional inventory is exampled which could form the basis for regional and (collectively) national environmental accounting.