An ecologically healthy river is a river that retains its major ecological features and functioning similar to that prior to European settlement and which would be able to sustain these characteristics into the future.

It is one which has flow regimes, water quality and channel characteristics such that:

• in the river and along its banks, the majority of plant and animal species are native and the presence of exotic species is not a significant threat
• natural ecosystem processes are maintained
• major natural habitat features are represented and are maintained over time
• native river bank vegetation is sustainable along the majority of the river’s length
• native fish and other animals can move and migrate up and down the river
• linkages between river and floodplain and associated wetlands maintain ecological processes
• natural linkages with the sea or terminal lakes are maintained
• associated estuaries and terminal lake systems are productive ecosystems.[1]

By this definition, an ecologically healthy river need not be pristine. Change from the natural state can occur – in some cases, considerable change. There may be exotic species present. In some areas along the river, the riparian zone may be significantly reduced. The capacity for fish to move up and down the river may be provided in some cases by fishways (read a story about this). Limited areas of the floodplain may be disconnected from the river. However, overall, the major natural features, biodiversity and functions of a river are still present and will continue into the future.

An ecologically healthy river is one where some aspects of river condition may have been traded off to provide for human use. Essentially, it is a river where a balance may have been struck between human use and the ecology of the river – a balance where the integrity of the system is still preserved, a reasonable level of human needs can be met, and where both can be sustained into the future.