Based on monitoring data for the period 2006–2008, five Slovenian marine water bodies were classified as being in a poor chemical state. This state was determined by values that exceeded the environmental standard of the quality of tributyltin compounds, which have been monitored at the level of the European Union since 2007. Three marine water bodies have been determined to be in a good or very good ecological state.
In accordance with the Water Directive and national regulations (Rules of monitoring the status of surface water), the chemical (classified into two categories) and ecological (classified into five categories) state of seawater is examined in order to determine its quality.
The chemical state is expressed as the concentration of priority and priority hazardous substances in surface water. These substances have been selected due to their widespread use and their increased concentrations in surface water.
The ecological state is expressed as the quality of structure and functioning of water ecosystems connected with surface waters. An assessment of the ecological state of surface water is based on identifying the change in values of physical, chemical, biological and hydromorphological elements compared to the reference state, i.e. the state without or with almost no disturbances. As the reference state depends on natural conditions and characteristics, the assessment is based on the ‘type-specific approach’ in which waters are initially classified into ecological types according to natural conditions and characteristics.
Due to a change in methodology, the indicator is not directly comparable to the MR06 indicator Chemical and trophic state of the sea, presented in previous years.