The measurements took place in June in Gdańsk in the Jelitkowo district at the mouth of the Gdańsk Bay. In the area of measurements were located the Jelitkowska reservoir and Oliwski stream. During the measurements, the students performed bottom sounding in two cross-sections of the stream, measurement of the flow velocity with the use of hydrometric mills in these cross-sections, and measurement of surface velocity using floats and a stopwatch. Moreover, in order to determine the longitudinal slope of the water level, height measurements were made with a technical level. In addition, in one of the cross-sections located at the outflow from the reservoir, measurements of the load of the overflow with a sharp edge were made.