1. Indicators are crucial to many socio-political schemes for portraying environmental influences of society. For example, the OECD model for State of the Environment Reporting uses three different sorts of indicators (pressure, condition, response) to differentiate the present condition of the environment from the anthropogenic pressures upon it and from any societal responses made to alleviate those pressures (thereby improving aspects of the overall condition).
2. These sorts of indicators have a fundamental technical basis in the science supporting their exposition and usage. However, the criteria used in interpreting the indicator values are likely to be set by considerations that go beyond scientific grounds. That is, indicators are socially determined in the end. However, many scientists find it difficult to involve the public in such reporting.
3. Scientists who are uncomfortable with this non-technical use of their indicator constructs should recognize that it is merely another manifestation of the overall broadening of environmental concern termed ‘ecosystem health’. The emerging field of ecosystem health seeks to take our technical understanding of how the environment functions and combine it with socio-economic goals, using a human health metaphor and an ethical underpinning.
4. River health might be better served by adopting a veterinary approach rather than the model of human health. This is because, like animals, riverine environments come in many different forms and cannot complain of ill health. Desirable interventions will vary with the uses to which we wish to put a river and our reasons for being concerned about a river’s health. A framework for this diagnostic approach is presented.
5. An enormous challenge lies ahead in integrating the various measurements of riverine attributes that might together constitute ‘river health’. We need ways to cater for the pluralism of modern societies, and we need more dynamic assessments of river condition, possibly founded on studies of key ecological processes.