The characteristics of flow from the landfill near Sezana in the area of Kras were studied by the use of tracer test. In well permeable fissure on the karren surface near the landfill the fluorescent dye uranine was injected in order to study the directions and velocities of its flow through the karst aquifer. Monitoring of tracer concentrations in the period of one year and a half enabled us to make some conclusions about the dynamics of groundwater flow in the directions towards the Timava, Brojnica and Sardoc springs. Detailed observations were organised also at the Klarici pumping station, which is the main source of drinking water for the Kras region. Increased concentrations of tracer were measured only during extremely high waters. Different explanations are possible, but we can not exclude the possibility of a weak, not permanent underground water connection with the landfill. Calculation of the amount of recovered tracer confirmed the main flow direction towards the Timava springs (recovery rate 93%) and a secondary direction with lower flow velocity towards the Brojnica and Sardoc springs. Outflow through the Klarici pumping is estimated to only 0.003% of injected uranine.
