Water Quality in Slovenia - Agencija RS za okolje

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2.1.2
W A T E R Q U A L I T Y I N S L O V E N I A
River Quality Assessment Using Saprobic Index and Beginnings of Ecological
Status Evaluation
In Slovenia, as well as in other European countries, the methodology for the assessment of the
ecological status of the rivers according to the Water Framework Directive is currently in preparation.
Until 2005, the biological quality of rivers was evaluated using the saprobic index, which primarily
shows the organic pollution. The Pantle and Buck method was used, with a modification according
to the Zelinka and Marvan method (25, 26) using calculation of the saprobic index (SI) value of the
biocenoses of benthic invertebrates and phytobenthos. The saprobic index (SI) value increases from
one to four with the deterioration of living conditions. For every analysed sample, the saprobic index
(SI) is calculated using the saprobic value, frequency and indicative weight of taxon.
According to the index value, each monitoring site is classified into an appropriate quality class (Table 4).
Table 4: Quality classes according to the saprobic index value
Quality class SI value Saprobic level River quality description
1 1.0 - 1.5 oligosaprobic uncharged to very little charged
1-2 1.51- 1.8
oligosaprobic to
betamesosaprobic
little charged
2 1.81- 2.3 betamesosaprobic moderately charged
2-3 2.31- 2.7
betamesosaprobic to
alfamesosaprobic
critically charged
3 2.71- 3.2 alfamesosaprobic heavily polluted
3-4 3.21- 3.5
alfamesosaprobic to
polysaprobic
very heavily polluted
4 3.51- 4.0 polysaprobic excessively polluted
The saprobic quality evaluation at selected monitoring sites in 2005 is shown in Map 2.
In comparison with 2004, the saprobic quality of rivers was improved in 2005. Based on the results of
saprobic analyses conducted in 42 rivers and at 69 different monitoring sites, most of the monitoring
sites are classified as uncharged to very little charged, and only one monitoring site is classified as
heavily polluted (the Rinža in Kočevje). There were neither very heavily polluted nor excessively
polluted rivers in 2005.
Sampling
A dragonfly