The rate of chromosome aberrations has been studied in higher aquatic plants: common reed, sagittaria, flowering rush and manna. The main water bodies were Glubokoye and Dalekoye-1 Lakes (left-bank flood lands of the Pripyat River), Azbuchin Lake and Yanovsky Crawl (right-bank flood lands of the Pripyat River), Cooling Pond of the Chernobyl NPP as well as Pripyat and Uzh Rivers. In decreasing sequence due to the absorbed dose rate for hydrobionts the first were water bodies of the left-bank flood lands of the Pripyat River, the second ones from right-bank flood lands. The highest chromosome aberrations rate in root meristems was registered in plants from lakes within the left-bank flood lands of the Pripyat River, the lowest one – in plants from the Pripyat and Uzh Rivers. The chromosome aberration rate in closed and slow-running water bodies within the right-bank flood lands of the Pripyat River was in 3–4 times higher than spontaneous mutagenesis level. It seems that spectrum of the main types of chromosome damages in plants of right-bank flood lands determines by chemical mutagens. The type of chromosome damages distribution in plants of the left-bank flood lands points to practically equivalent effects of radiation and chemical factors.