Summary:

On Trzebuńka stream, in Stróża village, the project of lowering of 4.0 m and restoring the check dam has been executed. The structure downstream was redesigned to form rapids, made of stones embedded in the "grouted rock" construction. Now, the whole construction of 12 small water reservoirs forms a kind of long fish pass. The preliminary results of stream channel evolution on Trzebuńka stream above the restored check dam are presented in the paper. There are described the local cases of check dam liquidation or restoration in the World. However, there are still many questions concerning the response of stream channel to such technical intervention. The problem of rate of sediment displacement in the reservoir and the consequent erosion base reduction for the channel above is discussed. The field measurements and observation show that two years after check dam lowering and emptying the sediment reservoir on Trzebuńka stream the transformation of new formed channel upstream the new structure is dynamic. At the length of 180.0 m upstream the new dam the bank erosion is significant. Just above 200.0 m upstream from the structure the channel is stable.