Indicators for a good status of waters

Lakes, rivers and the sea are complex ecosystems, and many different aspects must be studied and examined to assess their status.

A five-step scale is used to assess the status of lakes, rivers and coastal waters, where ‘high’ is the best grade and ‘bad’ the lowest, with ‘good’, ‘moderate’ and ‘poor’ grades in between.

The objective of river basin management is to ensure that the status of all surface waters is at least good, and that it does not deteriorate. More precisely, the aim set for all EU Member States is a good ecological and chemical of status of waters.

Ecological status is assessed by examining algae, aquatic plans, benthic animals and fish living in the water. This assessment can focus on the species composition as a whole, the abundance of different species or selected indicator species. Specific water quality factors (including phosphorus and nitrogen concentration) and any significant changes (including regulation and the barrier effects of dams) are also taken into consideration.

Chemical status is assessed on the basis of whether the maximum concentrations determined for certain hazardous or harmful chemicals and metals are exceeded.

Once all data have been gathered, the status class in which the water body in question would be placed is calculated in comparison to an area whose condition is as natural as possible. The final assessment is produced by an expert who also accounts for any gaps in the data, additional information and other case-specific circumstances.

Image: Oulu University of Applied Sciences