- To meet the objective of the EEA monitoring network there is an explicit need to try and relate differences in water quality and quantity to human activities in catchments, and thereby try to demonstrate cause/effect relationships. The addition of supportive activity information will add a further layer of difficulty to implementing the network. There will, therefore be key determinants (primary and secondary) that will provide the information to address the questions. There is, therefore, clear overlap with work being undertaken by other Topic Centres, for example those on Catalogue of Data Sources and on Land Cover.
- The clear understanding is that the monitoring network will be based where possible on existing national and international networks, use existing sources of monitoring information and create, only if necessary, an EEA database of aggregated rather than of non-aggregated data.
- Use of information from stations used in current international monitoring requirements and programmes such as, in the case of rivers, the Exchange of Information Decisions (77/95/EEC and 86/574/EEC) which aim to provide surveillance type information. This database has now been merged with the rivers database created by the Agencys Task Force for the Dobrí assessment report.
- Use sampling stations and monitoring information obtained nationally to demonstrate compliance with EC Directives such as the Freshwater Fish Directive.
- Current national classification schemes, where they exist, could perhaps (in theory) be translated to a unified European scale.
- An ambitious option is to sample and measure all water bodies in a consistent and comparable way which would clearly be very expensive to undertake and co-ordinate, and difficult to manage, interpret and report.
- Sub-sample a representative portion of the total water resources. This would be aided by stratifying the total population (e.g. all rivers) into relativity homogenous sub-strata.
- Information from European Commission directives is not suitable as:
- The data are not comparable because the degree of comparability will depend on the interpretation of the designation rules and national differences of how these are implemented.
- The data are not representative because in the directives which require routine monitoring the requirements are generally site specific, either at sites designated for a specific use, sites affected by a specific discharge, or, for the Exchange of Information Decisions, agreed sites in main rivers. As the choice of sampling location is, for some directives, related to areas designated by the Member States rather than by the European Commission, it is unlikely that, for those directives, a comparison of quality across Europe of these designated waters will give a complete picture of quality.
- The first three options would not necessarily give a representative view of Europes water resources, and method and data comparability would be an important issue to address. The latter option is the preferred one and is recommended for acceptance by the EEA and its Member States.
- There is a need for different types of monitoring stations to be included in the networks.
- Reference stations should be established on rivers in natural catchments with little or no human activity and with greater than 90% natural landscape. It is likely that such stations will not be present in some parts of Europe.
- Representative stations that can give a spatial and temporal general assessment of quality across Europe.
- Impact stations could form part of the representative network with the collection of supportive and interpretative information, or could form separate impact strata.
- Flux stations established where rivers discharge into sea, or cross-national boundaries, or there is interchange between surface and groundwater.
- Baseline stations may also be required to characterise the generality of run-off behaviour of the region or country.
- For the lakes and reservoirs network reference, representative and impacted lakes and reservoirs should be selected.
- The largest and most important national rivers, lakes and reservoirs should also be included within the monitoring networks.
- For groundwater there should be reference and representative stations that would deliver general information about the quality and quantity, and cover the entire area of each Member State. All major national aquifers should be covered. Reference stations should be established in areas not influenced by groundwater pumping and other anthropogenic activities. In some areas within the EEA (small countries or in densely populated areas) it will not be possible to establish reference stations.
- It will be important to confirm, that the monitoring wells, which are chosen for the groundwater network, should have been designed and constructed in a similar way so it is possible to compare the results from all the Member States.
- Ideally sampling frequency would be based on an assessment of determinant variability and the desired level of precision in the information. These aspects should be looked at in the pilot project and during the subsequent progressive implementation of the network.
- Once the network is implemented, monitoring meta-data should be made available to the Agency in the form of summary statistics and measures of data variability to allow assessments of data quality and comparability.
- Groups of primary and secondary determinants have been identified for surface and groundwater. Substances such as pesticides, other synthetic organic substances and heavy metals should be selected on the basis of their use in the catchment of interest. In addition supportive data on catchment characteristics and land use will be required and should be collected in comparable ways.
- The Topic Centre on Catalogue of Data Sources is currently working on many aspects of the environmental information network and there will need to be close liaison with the Topic Centre on Inland Waters. For example, there must be a common language for determinants, sampled media and units, usually codified in a data dictionary. Details of analytical procedures, methods, limits of detection, quality control may also have to be transferred to the Agency.
- Many of the river quality stations in national monitoring programmes are not located at or near gauging stations, and the requirement for water flow data may reduce the number of possible stations, especially in the case of small rivers and reference stations.
- The Nordic countries measure chemical oxygen demand instead of biochemical oxygen demand, and dissolved oxygen is not routinely measured. In addition, biochemical oxygen demand and chemical oxygen demand are analysed by many different methods. Some standardisation will be necessary to ensure that these data are comparable at an EEA level.
- In some countries total nitrogen is measured instead of nitrate, especially in the Nordic countries with relative low nitrate levels and relative high organic nitrogen levels. In others soluble reactive phosphate is measured instead of total phosphorus.
- In several countries there is no national lake/reservoir monitoring programme. However, in some of these countries local authorities monitor the water quality of lakes/reservoirs, and it should be possible to select the required number of water bodies for the EEA network from the local networks.
- In one country there is no national monitoring network for groundwater quality.
The desire to relate differences in quality and quantity to potential causal agents, that is establish cause and effect relationships raises many difficult technical issues and points of debate.
Any monitoring information received by the Agency will need validation. Key aspects such as statistical confidence, sampling windows and frequencies, sampling methodologies and analysis (e.g. performance, quality assurance, limits of detection) will need to be assessed, so that judgements can be made on the validity of comparisons and differences.
There are a number of options on how the network can be developed: