The drainage basin of mining lakes mainly consists of dumped sediments. These sediments vary greatly in terms of grain size, hydraulic conductivity and chemical composition. Groundwater flow assessment for this heterogeneous material is problematic, particularly at certain locations, but seepage measurements can help to explain the hydrodynamic and geochemical processes in more detail. Two closely investigated mining lakes were chosen to evaluate seepage meter measurements in order to enhance understanding of the groundwater flow into these lakes.