The Water Directors of European countries agreed to set up a specific Ad-hoc Task Group (ATG) on best practice and guidance to deal with hydromorphology. One of the core activities of the Working Group (WG) ECOSTAT of the WFD CIS has been to compare the ecological quality expected by different countries for water bodies impacted by water storage. This report is based on information collected via a template on mitigation measures for water bodies impacted by water storage, which was completed by 23 countries.