In 2014, 21 out of 22 sections of surface waters met water quality limit values set for assessing the capability of water to support freshwater fish life.
Inapropriate water quality was detected in the cyprinid section of the Mura River between the road bridge in Petanjci and its confluence with the Ščavnica tributary (Mura Mota measurement site) due to excessive concentrations of ammonia, measured on 8 July 2014. The limit value for ammonia in cyprinid waters is 0.025 mg NH3/l, while the measured concentration was 0.043 mg NH3/l.
In five sections (23%), water quality met the limit as well as the recommended values. In other sections, nitrite concentrations were the most frequently exceeded values, while ammonium concentrations were frequently exceeded in the salmonid sections.
In 2005, a total of 22 sections (13 for salmonid and 9 for cyprinid species) of inland surface water that are important for freshwater fish species were designated in Slovenia (Rules on the designation of surface water sections important for freshwater fish species, Official Gazette of the Republic of Slovenia, No. 28/05). The sections of salmonid surface waters support salmonid fish species such as trout, grayling and huchen, while the sections of cyprinid surface waters support cyprinid fish species such as carp, pike, perch, etc. The purpose of designation of those sections is to protect or improve the quality of water that supports freshwater fish species.
In the above-mentioned sections, the Environment Agency of the Republic of Slovenia monitors the quality of water in accordance with the Rules on the monitoring of the quality of surface waters supporting fish life (Official Gazette of the Republic of Slovenia, No. 71/02). National regulations are based on Directive 2006/44/EC on the quality of fresh waters needing protection or improvement in order to support fish life. The aim of the Directive is to protect or improve the quality of those running or standing fresh waters that support or, if pollution were reduced or eliminated, would become capable of supporting, fish belonging to indigenous species offering natural diversity and species whose presence is seen as desirable for water management purposes by the competent authorities of the Member States.
The suitability of water to support freshwater fish species is assessed with regard to compliance with recommended and limit values of parameters defined by the Decree on the quality required of surface waters supporting fresh-water fish life (Official Gazette of the Republic of Slovenia, No. 46/02). The assessment covers parameters that affect the living conditions of freshwater fish species, such as the oxygen content, pH value, suspended matter, biochemical oxygen demand, the content of phosphorous, nitrite, ammonia, ammonium, free chlorine, dissolved copper and dissolved zinc. The quality of salmonid or cyprinid water is not suitable and is deemed to be over polluted when the measured values exceed limit values defined by the Decree on the quality required of surface waters supporting fresh-water fish life (Official Gazette of the Republic of Slovenia, No. 46/02).
Water quality in salmonid and cyprinid sections is assessed as suitable when all parameters are below the limit values defined by the above-stated Decree. Water quality in salmonid and cyprinid sections is assessed as unsuitable when one of the parameters exceeds the limit value defined by the Decree. Water quality in salmonid and cyprinid sections is assessed as very good when values of all parameters are below limit values as well as below recommended values.
Standardised Database for Water Quality Monitoring, Slovenian Water Agency, 2015
Standardised Database for Water Quality Monitoring, Slovenian Environment Agency, 2015
|ustreza mejni vrednosti in ne ustreza priporočeni vrednosti||number of sections||18||16||19||17||16||17||18||17||16|
|ne ustreza niti mejni vrednosti niti priporočeni vrednosti||number of sections||1||1||0||0||1||1||2||1||1|
To preserve the quality of waters supporting important freshwater fish species.