Aquatic plants are one of the main components of biota of water bodies and streams, which holds an important role in the migration process and circuit of the chemical elements. Aquatic plants are able to accumulate enough large quantities of metals, which allow their use as biomonitor. The contents of many metals in aquatic plants are highly correlated with their contents in reservoir water and silt: r = 0.87-0.91. The dynamics of trace element accumulation depends on seasonal factors. From the beginning of spring to the end of summer and beginning of autumn, the concentrations of trace elements increased by large increments, while in autumn, with the decrease of water temperature below 10oC, an opposite effect was observed. After plant death, a significant part of accumulated trace elements are released into the water, in most cases this being associated with organic compounds. More than one half of the amount of trace elements is deposited in the bottom sediments.