Water Quality in Slovenia - Agencija RS za okolje

2 Surface Waters
2.1
2.1.1
Quality of Rivers
The monitoring of river water quality (5, 6) is carried out on the basis of laws and regulations (2, 7,
8) in accordance with the requirements of the Water Framework Directive (1) and other guidelines
and professional instructions for the establishment and implementation of the monitoring (9, 10,
11, 12, 13, 14). In rivers, a total of 135 water bodies were determined in 2005, 110 of them in the
Danube river basin district and 25 in the Adriatic river basin district (15). In some of these water
bodies, monitoring had already been carried out in the past, and in the others, the monitoring and
status evaluation for the purpose of the first river basin management plan will be carried out for the
first time in the period 2007-2009. The chemical and ecological status will have to be evaluated in
accordance with the Water Framework Directive.
In Slovenia, the chemical status of rivers has been evaluated in accordance with the Regulation on
the chemical status of surface waters (7) since 2002. The Regulation determines the limit values
of parameters and criteria for the assessment of the chemical status. In the future, this regulation
will have to be changed as a directive (16), which will in the course of preparation, determine
environmental quality standards for the substances that have, at a European level, been classified as
hazardous (priority list of hazardous substances).
In past years the assessment of river water quality was based on biological analyses of phytobenthos
and benthic invertebrate fauna, and carried out according to the saprobic system which, above
all, indicates the influences of organic pollution in waters. For the period from 1996 to 2005, the
status of Slovenian rivers in relation to biological analyses is presented according to this system. The
ecological status assessment methods are still under development. Sampling and analyses for some
biological quality elements are carried out in compliance with ready-prepared expert groundwork
(17, 18, 19, 20, 21, 22). For the year 2006, the first results of organic pollution evaluation on the basis
of benthic invertebrate fauna and phytobenthos have already been presented.
All evaluations are stated for a monitoring site and not for the water body, as required by the Water
Framework Directive, since not all evaluations of the chemical status for all water bodies are available
at the moment, and neither is the methodology for the evaluation of the ecological status for all
biological elements and pressures.
Evaluation of Chemical Status of Rivers
The chemical status must be determined:
• for any river or its part where the catchment area reaches 2500 km2 ,
• for any water body that is substantially polluted by one or more parameters from the priority or
indicative list of parameters,
• for any water body into which waste waters containing priority substances are discharged,
• for water bodies crossed by the state border.
According to the Regulation on the chemical status of surface waters (7), physico-chemical parameters
must be measured at all monitoring sites. In addition, priority substances are regularly measured
at all basic monitoring sites; and at all basic and additional monitoring sites, those parameters are
measured for which increased pollution has been established on the basis of results obtained in the
monitoring of river water quality or on the basis of the data published in annual reports on emission
monitoring of sources of pollution.
The chemical status of a surface water body is determined on the basis of the calculation of the
average annual value of parameters for which the limit values listed in Table 1 are defined in the
Regulation (7).
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