Basic hydraulic parameters such as shear stress, streampower, unit stream power and water velocities were calculated and measured within the region of a drop hydraulic structure erected on the Kasinczanka stream in the Polish Carpathians. Besides examining the hydrodynamics of the stream the study investigated also the distribution of grain size in the bed-load at the upstream and downstream aprons of the structure. It was revealed that grains deposited at the upstream apron were finer than those deposited at the downstream apron. At the same time, shear stresses and unit streampower values were found to be quite stable upstream of the drop structure, but to change significantly along the stream channel downstream of the structure’s energy dissipating pool.