The first Swedish water quality assessment criteria were determined in 2007. These were developed by a group comprising experts from Swedish universities and water authorities as well as consultants, all commissioned by the Swedish Environmental Protection Agency. These assessment criteria were applied when reporting the first water quality assessment to the EC.
If all requirements for implementing the WFD and the associated Swedish regulations are in place, why is a new research programme required? Such a programme is needed because it takes time to develop a practicable and reliable system to assess water quality, and application of the existing assessment criteria has identified a number of areas that need further development. The objectives of the WATERS research programme are to build on existing experience, improve the applicability of the assessment criteria, and reduce the uncertainty in water quality assessments. The programme focuses particularly on the following topics:
Choice of quality elements and indicators
Existing Swedish assessment criteria outline how a number of quality elements (e.g., macrophytes) and measurement parameters that form the basis of indicators (e.g., maximum depth distribution) should be implemented. Choice of quality elements is largely regulated by the WFD. However, there are many options regarding what indicators to use.
WATERS will investigate the possibility of including new indicators and quality elements in the assessment criteria and of refining existing ones. For example, fish is already used as a quality element when assessing Swedish inland waters but not coastal waters. The programme will now evaluate the possibility of using fish as a quality element for coastal areas as well. Read more.
Links between biological indicators and human pressures
If the biological parameters measured in environmental monitoring programmes are to give a good indication of water status, it is necessary to understand how they react and respond to various disturbances. Only then can they be properly labelled indicators. However, for several biological indicators, the link to disturbances caused by human activity is at present relatively weak.
A central objective of WATERS is to improve our knowledge of how the biological indicators respond to human pressures. This will primarily be done through gradient studies. In these studies, the indicator responses to various levels of human pressure will be evaluated in situ, for example, in a series of lakes subject to various levels of eutrophication or in the outflow from a river drainage basin. Read more about the planned gradient studies in inland and coastal waters.
Methods for defining reference conditions and class boundaries
Existing Swedish assessment criteria were largely developed for the individual quality elements in isolation. The methods used to define reference conditions and class boundaries therefore differ between quality elements as well as between coastal and inland waters. Some differences occur because of natural differences in supporting data and measured parameters, and because what are considered acceptable changes within the concept of “good status” differ between quality elements. However, the differences are partly caused by lack of time and coordination rather than being true differences in supporting information or measured parameters.
WATERS aims to harmonize the methods used to define reference conditions and class boundaries, for example, by testing a number of existing models. Read more.
How to consider uncertainty
If a water body is assessed as being in “good status”– how certain can we that the assessment is correct? Water status classification includes a number of steps that introduce uncertainty into the assessment, for example, sample handling and choice of measuring station. In addition, reference conditions and class boundaries are often based on models and expert judgement, and the integrated assessment of quality elements also introduces uncertainty into the overall status classification.
WATERS will identify and quantify various sources of uncertainty and develop a system for evaluating uncertainty and estimating how it influences the overall water status classification. Read more.
Tools for integrated assessment
In accordance with the WFD, the existing Swedish assessment criteria are based on the “one out – all out” principle. This principle implies that the lowest-rated quality element determines the overall water status of a water body. This also implies that all quality elements, and indirectly the indicators that form the basis of assessment, are given the same weight in the integrated assessment. However, the indicators measured do not necessarily have the same significance when it comes to classifying the water quality.
WATERS will develop guidelines and tools for integrated assessment that take into account the ecological relevance of indicators and quality elements and that also considers potential interactions between them. Read more.
