Use of earth observation tools in support of the WFD : state of play for ecological status monitoring and assessment in surface waters of Europe

This report maps the use level of Earth observations (EO, satellite observations) in ecological status assessment for WFD (ES). Altogether 45 experts from 22 European countries replied to a survey, and 100 participants discussed its outcomes in a Workshop (9-11/2024). According to the survey, EO data are not presently used for ES assessment in most MS, while there are very good EO results to support it. In most MS there have been R&D activities, training and workshops among EO experts and authorities responsible for ES assessment. There are already some national interfaces that provide EO water quality data, either for ES assessment purposes, or to promote the EO use for water quality management in general. In MS that use EO for ES assessment (FI, SE, BE), EO is used either as supporting information via the 'expert judgement' rule or via modelling. EO is mainly used as water body-specific results and indicators (Chl-a most). Three major obstacles were identified for incorporating EO as formal WFD monitoring method: 1. there are no common guidelines on how to utilise EO for WFD reporting, 2. there are legal issues in WFD (EO use is not foreseen in current monitoring guidelines), and 3. authorities are not well informed about EO tools. In most MS there is willingness to use EO for WFD, but without clear plan. The EO benefits are clear, as 90% replied that EO can increase spatial & temporal coverage, cost-efficiency, and confidence for ES assessment. EO can also help the harmonisation of WFD with other Directives (MSFD, BD, HD).