This European Standard provides guidance on characterizing the modifications of the hydromorphological features of TraC waters described in EN 16503, enabling consistent comparisons of hydromorphological modification between TraC waters within a country and between different countries in Europe. Its primary aim is to assess departure from naturalness as a result of human pressures on TraC hydromorphology, and it suggests suitable sources of information that may contribute to describing the modification of hydromorphological features. The procedures set out in this standard will encourage the objective assessment and reporting of the variability in transitional and coastal waters, and contribute to the work needed to implement the WFD and the MSFD; however, it does not replace methods that have been developed for local assessment and reporting.