The article deals with the hydraulic investigation of a shaft spillway on the Labská Dam. A physical model of the right shaft spillway of the Labská Dam was built in the Hydrotechnical Laboratory and placed in the measuring flume. The hydrotechnical investigation describes the measurement of levels, discharges and pressures in the spillway and in the outlet culvert. Five types of technical options of the shaft spillway modifications were evaluated on the model. The results of the investigation include: the comparison of theoretical and measured consumption curves and comparison of pressure patterns along the whole length of the outlet culvert for all shaft spillway modifications.