As of: March 2006

Ecological quality for aquatic life

Rivers are nature’s lifelines. Without them, life would be considerably poorer. This applies to the animal and plant worlds and to the world of human experience, to human uses at or near water and the preservation of human life. Without intact rivers and lakes, worlds of life and experience become impoverished and the diversity of flora and fauna suffers.

Ecological functionality, and hence the conditions for life in and near our lakes and rivers, are to a large extent determined by water quality, run-off dynamics and structural conditions. The Federal Water Act requires that bodies of water be safeguarded as part of the natural regime and as a habitat for plants and animals; all avoidable impairment of their ecological function is to be avoided.

This new approach to the ecological attributes of bodies of water considers not only the quality of the water, but also biological indicators. These indicators differ depending on the type of water body: they may be fish, small aquatic animals ("macrozoobenthos"), aquatic plants, algae or vegetable plankton. The ecological status of a lake is judged by the extent to which its biotic community differs from that of a comparable unpolluted lake. Assessment of rivers is based on the presence of the appropriate characteristic biotic community, depending on whether the river concerned is a mountain stream or a major lowland river. The smaller the difference between the river in view and a natural river or stream, the better its condition is judged to be. Another important factor here is whether migratory fish have unobstructed access to suitable breeding grounds in keeping with their life cycle. Only if this is the case can self-sustaining fish populations become established.

Further Information:
- "Gewässerstrukturkarte" (only in German)
- "Gewässergütekarte" (only in German)