In this paper an effort has been taken to bind usefulness of water plants – as bioindicators of running waters eutrophication – with observations concerning influence of modifications in hydromorphology of watercourses on species diversity of macrophytes occurring in them. Research was conducted in four upland rivers and streams located in south Poland. Research results indicate that slight anthropogenic modifications in river channels cause increase of macrophyte species diversity in relation to natural conditions, but advanced modifications cause ecological degradation of watercourses below the level of initial stage. Results of assessment also indicate that there is a need of developing the Macrophyte Method of River Assessment in direction of immediate connections between the value of Macrophyte River Index and physicochemical state of surface waters
