Summary:

This paper presents an assessment on the ecological status of various low-land watercourses found in Lower Silesia, determined by using aquatic macro-phytes as the primary biological indicator on the health and condition of such wa-tercourses. Field studies were conducted during 2007-2008 on various unregulated, conserved and regulated watercourses. Research included identifying the species of aquatic macrophytes found in the streambed as well as determining the degree of coverage. On this basis was the RI index calculated and the ecological status of watercourses defined.
The field studies showed, that the watercourse's ecological status depends on many factor. To identify those factors we analyzed the correlation between the class of watercourse's ecological status and technical parameters like: bottom width, watercourse's depth, inclination of the slope and longitudinal profile. The analysis showed that the impact of channel parameters on the ecological condition of watercourses was similar in the case of natural watercourses and those that were transformed as a result of technical interference. However based on the survey cannot be found, that the technical parameters of watercourse's bed shaped as a result of regulatory and maintenance works affect the improvement or the dete-rioration of the ecological status. This follows from the fact that the effect of those interferences is dynamic. Therefore assessing the ecological status of watercourses must always be taken into account the time that elapsed from the technical inter-ference in the watercourse's bed.