14 Surface Water Eutrophication in Poland: Assessment and Prevention
325
14.2 Methodological Problems of Eutrophication
Assessment
14.2.1 Assessment Approach According to Legislative
Documents
To assess the dynamics of eutrophication development, it is necessary to collect
extended reliable long-term monitoring data bank concerning the specific indicators
of eutrophication. As shows the state of knowledge analysis, an appropriate assessment of water trophic status, the scale of negative changes in aquatic ecosystem and
water quality is difficult due to the lack of sufficient long-term results of hydrobiological parameters observations. In addition, the system of eutrophication monitoring
is unsatisfactory: there is no uniform methodological approach to trophic status
assessment, the lack of reliable and low-cost eutrophication indicators.
Regarding the European legislation on the status of aquatic environment, it
should be noted that many EU directives impose an obligation on member states
to realize the monitoring of the parameters important for eutrophication assessment
and appropriate recommendations on their limit values. Although only the Directive
concerning urban waste-water treatment (91/271/EEC) [18] and Nitrates Directive
(91/676/EEC) [19] contains explicitly the eutrophication assessment requirements:
in 91/271/EEC Directive through the need to identify the “sensitive areas”, i.e. “sensitive water bodies”, and in the 91/676/EEC Directive by identifying “contaminated
waters’” and consequently, the sensitive zones. The Water Framework Directive WFD
(2000/60/EC) [20] maintains the recommendations of 91/676/EEC and 91/271/EEC
Directives and additionally includes the recommendation to realize the eutrophication assessment as part of ecological status assessment. Recommendations for the
assessment of eutrophication indicators are also included in some other EU Directives
(Table 14.2) [18–23].
None of these directives gives a unified definition of the process, nor a methodology for its evaluation, except this, various indicators with different limit values
are applied in different countries to assess the course of this phenomenon. In the
interpretation of EU Directives, eutrophication is an undesirable phenomenon and
does not require the precise definition of trophic state, but only the statement of the
occurrence of adverse changes in water status. The comparison of the methods of
surface water trophic status assessment according to the recommendations of WFD,
Wastewater Directive and Nitrate Directive in terms of “ecological status”, “sensitive
area” and” contaminated waters” is presented in Table 14.3.
The assessment of trophic state according to the recommendations of different EU
Directives often gives contradictory results. This is mainly the effect of the difference
in adopted assumptions and approaches to assessing this phenomenon and practical
objectives of the assessment. The different set of suggested trophic indicators and
different interpretation of their limit values also contributes to the discrepancy of
assessment results [23]. The disadvantage of these legislative recommendations lies
325
14.2 Methodological Problems of Eutrophication
Assessment
14.2.1 Assessment Approach According to Legislative
Documents
To assess the dynamics of eutrophication development, it is necessary to collect
extended reliable long-term monitoring data bank concerning the specific indicators
of eutrophication. As shows the state of knowledge analysis, an appropriate assessment of water trophic status, the scale of negative changes in aquatic ecosystem and
water quality is difficult due to the lack of sufficient long-term results of hydrobiological parameters observations. In addition, the system of eutrophication monitoring
is unsatisfactory: there is no uniform methodological approach to trophic status
assessment, the lack of reliable and low-cost eutrophication indicators.
Regarding the European legislation on the status of aquatic environment, it
should be noted that many EU directives impose an obligation on member states
to realize the monitoring of the parameters important for eutrophication assessment
and appropriate recommendations on their limit values. Although only the Directive
concerning urban waste-water treatment (91/271/EEC) [18] and Nitrates Directive
(91/676/EEC) [19] contains explicitly the eutrophication assessment requirements:
in 91/271/EEC Directive through the need to identify the “sensitive areas”, i.e. “sensitive water bodies”, and in the 91/676/EEC Directive by identifying “contaminated
waters’” and consequently, the sensitive zones. The Water Framework Directive WFD
(2000/60/EC) [20] maintains the recommendations of 91/676/EEC and 91/271/EEC
Directives and additionally includes the recommendation to realize the eutrophication assessment as part of ecological status assessment. Recommendations for the
assessment of eutrophication indicators are also included in some other EU Directives
(Table 14.2) [18–23].
None of these directives gives a unified definition of the process, nor a methodology for its evaluation, except this, various indicators with different limit values
are applied in different countries to assess the course of this phenomenon. In the
interpretation of EU Directives, eutrophication is an undesirable phenomenon and
does not require the precise definition of trophic state, but only the statement of the
occurrence of adverse changes in water status. The comparison of the methods of
surface water trophic status assessment according to the recommendations of WFD,
Wastewater Directive and Nitrate Directive in terms of “ecological status”, “sensitive
area” and” contaminated waters” is presented in Table 14.3.
The assessment of trophic state according to the recommendations of different EU
Directives often gives contradictory results. This is mainly the effect of the difference
in adopted assumptions and approaches to assessing this phenomenon and practical
objectives of the assessment. The different set of suggested trophic indicators and
different interpretation of their limit values also contributes to the discrepancy of
assessment results [23]. The disadvantage of these legislative recommendations lies