The operation of the Mining and Chemical Combine situated on the bank of the Yenisei River has resulted in intensive radioactive pollution of all components of the ecosystem by pollutants including tritium. Although tritium is considered to be little accumulated in bottom sediments and soils, it has been found that depending on the geochemical properties of soils tritium can be accumulated in some rocks due to binding with organic substances of the soil or penetrating into the layers of clay minerals and retaining in the interlayer space. Depending on the way of tritium inflow (water way or bottom sediments) it is distributed in plant parts non-uniformly. Here, in all the cases lamina dominates as the part of the plants most actively participating in photosynthesis. At constant tritium inflow to the Canada water weed biomass the intervention level for tritium was 2900 Bq/l.